Arduino nano every - 'TWCR' was not declared in this scope

Hello there,

I am using a OV7670 camera module (https://www.tinytronics.nl/shop/en/sensors/optical/cameras-and-scanners/ov7670-cmos-camera-module)
and want to see images on my pc. First of all, I know camera's and arduino's is not always a good idea, however I dont require a good quality nor an excellent frame rate.

I solved already one 'not declared in this scope' and now know that the code is written for uno, but can't seem to find any solutions for the TWCR error. So my question, is how to translate this code to be useable on arduino nano every (and every idea to improve the code or make it better for arduino nano is welcome!!)

Before you let your keen eye lose on my code you probably wonder why I don't use a Uno. Basically I need a small footprint and love the idea of being able to upgrade to an arduino 33 IOT and don't have to change any of the hardware. So basically, the specs of the arduino nano and hardware compatibility to be able to upgrade to a IOT device with the same form factor.

The code:

#include <arduino.h> //test

#include <stdint.h>
#include <avr/io.h>
#include <util/twi.h>
#include <util/delay.h>
#include <avr/pgmspace.h>


#define F_CPU 16000000UL
#define vga   0
#define qvga  1
#define qqvga   2
#define yuv422  0
#define rgb565  1
#define bayerRGB  2
#define camAddr_WR  0x42
#define camAddr_RD  0x43


/* Registers */

#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED       0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656  0x40    /* CCIR656 enable */

#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */

#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */ //REG mean address.
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */
#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB          0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV          0x00  /* YUV */

#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */
#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD         0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */
#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */
#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */


#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25    /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */
#define REG_HSYST   0x30  /* HSYNC rising edge delay */
#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */
#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */
#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */

/*

  This matrix defines how the colors are generated, must be

  tweaked to adjust hue and saturation.



  Order: v-red, v-green, v-blue, u-red, u-green, u-blue

  They are nine-bit signed quantities, with the sign bit

  stored in0x58.Sign for v-red is bit 0, and up from there.

*/

#define REG_CMATRIX_BASE  0x4f

#define CMATRIX_LEN           6
#define REG_CMATRIX_SIGN  0x58
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_CONTRAS         0x56  /* Contrast control */
#define REG_GFIX    0x69  /* Fix gain control */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */
#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */
#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define REG_GAIN    0x00  /* Gain lower 8 bits (rest in vref) */
#define REG_BLUE    0x01  /* blue gain */
#define REG_RED           0x02  /* red gain */
#define REG_VREF    0x03  /* Pieces of GAIN, VSTART, VSTOP */
#define REG_COM1    0x04  /* Control 1 */
#define COM1_CCIR656          0x40  /* CCIR656 enable */
#define REG_BAVE    0x05  /* U/B Average level */
#define REG_GbAVE   0x06  /* Y/Gb Average level */
#define REG_AECHH   0x07  /* AEC MS 5 bits */
#define REG_RAVE    0x08  /* V/R Average level */
#define REG_COM2    0x09  /* Control 2 */
#define COM2_SSLEEP         0x10  /* Soft sleep mode */
#define REG_PID           0x0a  /* Product ID MSB */
#define REG_VER           0x0b  /* Product ID LSB */
#define REG_COM3    0x0c  /* Control 3 */
#define COM3_SWAP         0x40  /* Byte swap */
#define COM3_SCALEEN          0x08  /* Enable scaling */
#define COM3_DCWEN          0x04  /* Enable downsamp/crop/window */
#define REG_COM4    0x0d  /* Control 4 */
#define REG_COM5    0x0e  /* All "reserved" */
#define REG_COM6    0x0f  /* Control 6 */
#define REG_AECH    0x10  /* More bits of AEC value */
#define REG_CLKRC   0x11  /* Clocl control */
#define CLK_EXT           0x40  /* Use external clock directly */
#define CLK_SCALE   0x3f  /* Mask for internal clock scale */
#define REG_COM7    0x12  /* Control 7 */
#define COM7_RESET          0x80  /* Register reset */
#define COM7_FMT_MASK         0x38
#define COM7_FMT_VGA          0x00
#define COM7_FMT_CIF          0x20  /* CIF format */

#define COM7_FMT_QVGA         0x10  /* QVGA format */
#define COM7_FMT_QCIF         0x08  /* QCIF format */
#define COM7_RGB    0x04  /* bits 0 and 2 - RGB format */
#define COM7_YUV    0x00  /* YUV */
#define COM7_BAYER          0x01  /* Bayer format */
#define COM7_PBAYER         0x05  /* "Processed bayer" */
#define REG_COM8    0x13  /* Control 8 */
#define COM8_FASTAEC          0x80  /* Enable fast AGC/AEC */
#define COM8_AECSTEP          0x40  /* Unlimited AEC step size */

#define COM8_BFILT    0x20  /* Band filter enable */
#define COM8_AGC    0x04  /* Auto gain enable */
#define COM8_AWB    0x02  /* White balance enable */
#define COM8_AEC    0x01  /* Auto exposure enable */
#define REG_COM9    0x14  /* Control 9- gain ceiling */
#define REG_COM10   0x15  /* Control 10 */
#define COM10_HSYNC         0x40  /* HSYNC instead of HREF */
#define COM10_PCLK_HB         0x20  /* Suppress PCLK on horiz blank */
#define COM10_HREF_REV          0x08  /* Reverse HREF */
#define COM10_VS_LEAD           0x04  /* VSYNC on clock leading edge */
#define COM10_VS_NEG          0x02  /* VSYNC negative */
#define COM10_HS_NEG          0x01  /* HSYNC negative */

#define REG_HSTART    0x17  /* Horiz start high bits */
#define REG_HSTOP   0x18  /* Horiz stop high bits */
#define REG_VSTART    0x19  /* Vert start high bits */
#define REG_VSTOP   0x1a  /* Vert stop high bits */
#define REG_PSHFT   0x1b  /* Pixel delay after HREF */
#define REG_MIDH    0x1c  /* Manuf. ID high */

#define REG_MIDL    0x1d  /* Manuf. ID low */
#define REG_MVFP    0x1e  /* Mirror / vflip */
#define MVFP_MIRROR         0x20  /* Mirror image */
#define MVFP_FLIP   0x10  /* Vertical flip */
#define REG_AEW           0x24  /* AGC upper limit */
#define REG_AEB           0x25  /* AGC lower limit */
#define REG_VPT           0x26  /* AGC/AEC fast mode op region */

#define REG_HSYST   0x30  /* HSYNC rising edge delay */

#define REG_HSYEN   0x31  /* HSYNC falling edge delay */
#define REG_HREF    0x32  /* HREF pieces */
#define REG_TSLB    0x3a  /* lots of stuff */
#define TSLB_YLAST    0x04  /* UYVY or VYUY - see com13 */
#define REG_COM11   0x3b  /* Control 11 */
#define COM11_NIGHT         0x80  /* NIght mode enable */
#define COM11_NMFR          0x60  /* Two bit NM frame rate */
#define COM11_HZAUTO          0x10  /* Auto detect 50/60 Hz */
#define COM11_50HZ          0x08  /* Manual 50Hz select */

#define COM11_EXP   0x02
#define REG_COM12   0x3c  /* Control 12 */
#define COM12_HREF          0x80  /* HREF always */
#define REG_COM13   0x3d  /* Control 13 */
#define COM13_GAMMA         0x80  /* Gamma enable */
#define COM13_UVSAT         0x40  /* UV saturation auto adjustment */
#define COM13_UVSWAP          0x01  /* V before U - w/TSLB */
#define REG_COM14   0x3e  /* Control 14 */
#define COM14_DCWEN         0x10  /* DCW/PCLK-scale enable */
#define REG_EDGE    0x3f  /* Edge enhancement factor */
#define REG_COM15   0x40  /* Control 15 */
#define COM15_R10F0         0x00  /* Data range 10 to F0 */

#define COM15_R01FE         0x80  /*      01 to FE */
#define COM15_R00FF         0xc0  /*      00 to FF */
#define COM15_RGB565          0x10  /* RGB565 output */
#define COM15_RGB555          0x30  /* RGB555 output */
#define REG_COM16   0x41  /* Control 16 */
#define COM16_AWBGAIN         0x08  /* AWB gain enable */
#define REG_COM17   0x42  /* Control 17 */
#define COM17_AECWIN          0xc0  /* AEC window - must match COM4 */
#define COM17_CBAR          0x08  /* DSP Color bar */


#define CMATRIX_LEN             6
#define REG_BRIGHT    0x55  /* Brightness */
#define REG_REG76   0x76  /* OV's name */
#define R76_BLKPCOR         0x80  /* Black pixel correction enable */

#define R76_WHTPCOR         0x40  /* White pixel correction enable */
#define REG_RGB444          0x8c  /* RGB 444 control */
#define R444_ENABLE         0x02  /* Turn on RGB444, overrides 5x5 */
#define R444_RGBX   0x01  /* Empty nibble at end */
#define REG_HAECC1    0x9f  /* Hist AEC/AGC control 1 */
#define REG_HAECC2    0xa0  /* Hist AEC/AGC control 2 */
#define REG_BD50MAX         0xa5  /* 50hz banding step limit */

#define REG_HAECC3    0xa6  /* Hist AEC/AGC control 3 */
#define REG_HAECC4    0xa7  /* Hist AEC/AGC control 4 */
#define REG_HAECC5    0xa8  /* Hist AEC/AGC control 5 */
#define REG_HAECC6    0xa9  /* Hist AEC/AGC control 6 */
#define REG_HAECC7    0xaa  /* Hist AEC/AGC control 7 */
#define REG_BD60MAX         0xab  /* 60hz banding step limit */
#define MTX1            0x4f  /* Matrix Coefficient 1 */
#define MTX2            0x50  /* Matrix Coefficient 2 */

#define MTX3            0x51  /* Matrix Coefficient 3 */
#define MTX4            0x52  /* Matrix Coefficient 4 */
#define MTX5            0x53  /* Matrix Coefficient 5 */
#define MTX6            0x54  /* Matrix Coefficient 6 */
#define REG_CONTRAS         0x56  /* Contrast control */
#define MTXS            0x58  /* Matrix Coefficient Sign */
#define AWBC7           0x59  /* AWB Control 7 */
#define AWBC8           0x5a  /* AWB Control 8 */
#define AWBC9           0x5b  /* AWB Control 9 */
#define AWBC10            0x5c  /* AWB Control 10 */
#define AWBC11            0x5d  /* AWB Control 11 */
#define AWBC12            0x5e  /* AWB Control 12 */

#define REG_GFI           0x69  /* Fix gain control */
#define GGAIN           0x6a  /* G Channel AWB Gain */
#define DBLV            0x6b
#define AWBCTR3           0x6c  /* AWB Control 3 */
#define AWBCTR2           0x6d  /* AWB Control 2 */
#define AWBCTR1           0x6e  /* AWB Control 1 */
#define AWBCTR0           0x6f  /* AWB Control 0 */


struct regval_list {

  uint8_t reg_num;

  uint16_t value;

};


const struct regval_list qvga_ov7670[] PROGMEM = {

  { REG_COM14, 0x19 },
  { 0x72, 0x11 },
  { 0x73, 0xf1 },


  { REG_HSTART, 0x16 },
  { REG_HSTOP, 0x04 },
  { REG_HREF, 0xa4 },
  { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a },
  { REG_VREF, 0x0a },


  { 0xff, 0xff }, /* END MARKER */

};


const struct regval_list yuv422_ov7670[] PROGMEM = {

  { REG_COM7, 0x0 },  /* Selects YUV mode */
  { REG_RGB444, 0 },  /* No RGB444 please */
  { REG_COM1, 0 },
  { REG_COM15, COM15_R00FF },
  { REG_COM9, 0x6A }, /* 128x gain ceiling; 0x8 is reserved bit */
  { 0x4f, 0x80 },   /* "matrix coefficient 1" */
  { 0x50, 0x80 },   /* "matrix coefficient 2" */
  { 0x51, 0 },    /* vb */
  { 0x52, 0x22 },   /* "matrix coefficient 4" */
  { 0x53, 0x5e },   /* "matrix coefficient 5" */
  { 0x54, 0x80 },   /* "matrix coefficient 6" */
  { REG_COM13, COM13_UVSAT },
  { 0xff, 0xff },   /* END MARKER */

};


const struct regval_list ov7670_default_regs[] PROGMEM = {//from the linux driver

  { REG_COM7, COM7_RESET },
  { REG_TSLB, 0x04 }, /* OV */
  { REG_COM7, 0 },  /* VGA */

  /*

    Set the hardware window.  These values from OV don't entirely

    make sense - hstop is less than hstart.  But they work...

  */

  { REG_HSTART, 0x13 }, { REG_HSTOP, 0x01 },
  { REG_HREF, 0xb6 }, { REG_VSTART, 0x02 },
  { REG_VSTOP, 0x7a }, { REG_VREF, 0x0a },
  { REG_COM3, 0 }, { REG_COM14, 0 },

  /* Mystery scaling numbers */

  { 0x70, 0x3a }, { 0x71, 0x35 },
  { 0x72, 0x11 }, { 0x73, 0xf0 },
  { 0xa2,/* 0x02 changed to 1*/1 }, { REG_COM10, 0x0 },

  /* Gamma curve values */

  { 0x7a, 0x20 }, { 0x7b, 0x10 },
  { 0x7c, 0x1e }, { 0x7d, 0x35 },
  { 0x7e, 0x5a }, { 0x7f, 0x69 },
  { 0x80, 0x76 }, { 0x81, 0x80 },
  { 0x82, 0x88 }, { 0x83, 0x8f },
  { 0x84, 0x96 }, { 0x85, 0xa3 },
  { 0x86, 0xaf }, { 0x87, 0xc4 },
  { 0x88, 0xd7 }, { 0x89, 0xe8 },

  /* AGC and AEC parameters.  Note we start by disabling those features,

    then turn them only after tweaking the values. */

  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP },
  { REG_GAIN, 0 }, { REG_AECH, 0 },
  { REG_COM4, 0x40 }, /* magic reserved bit */
  { REG_COM9, 0x18 }, /* 4x gain + magic rsvd bit */
  { REG_BD50MAX, 0x05 }, { REG_BD60MAX, 0x07 },
  { REG_AEW, 0x95 }, { REG_AEB, 0x33 },
  { REG_VPT, 0xe3 }, { REG_HAECC1, 0x78 },
  { REG_HAECC2, 0x68 }, { 0xa1, 0x03 }, /* magic */
  { REG_HAECC3, 0xd8 }, { REG_HAECC4, 0xd8 },
  { REG_HAECC5, 0xf0 }, { REG_HAECC6, 0x90 },
  { REG_HAECC7, 0x94 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC },
  { 0x30, 0 }, { 0x31, 0 },//disable some delays

  /* Almost all of these are magic "reserved" values.  */

  { REG_COM5, 0x61 }, { REG_COM6, 0x4b },
  { 0x16, 0x02 }, { REG_MVFP, 0x07 },
  { 0x21, 0x02 }, { 0x22, 0x91 },
  { 0x29, 0x07 }, { 0x33, 0x0b },
  { 0x35, 0x0b }, { 0x37, 0x1d },
  { 0x38, 0x71 }, { 0x39, 0x2a },
  { REG_COM12, 0x78 }, { 0x4d, 0x40 },
  { 0x4e, 0x20 }, { REG_GFIX, 0 },

  /*{0x6b, 0x4a},*/{ 0x74, 0x10 },

  { 0x8d, 0x4f }, { 0x8e, 0 },
  { 0x8f, 0 }, { 0x90, 0 },
  { 0x91, 0 }, { 0x96, 0 },
  { 0x9a, 0 }, { 0xb0, 0x84 },
  { 0xb1, 0x0c }, { 0xb2, 0x0e },
  { 0xb3, 0x82 }, { 0xb8, 0x0a },


  /* More reserved magic, some of which tweaks white balance */

  { 0x43, 0x0a }, { 0x44, 0xf0 },
  { 0x45, 0x34 }, { 0x46, 0x58 },
  { 0x47, 0x28 }, { 0x48, 0x3a },
  { 0x59, 0x88 }, { 0x5a, 0x88 },
  { 0x5b, 0x44 }, { 0x5c, 0x67 },
  { 0x5d, 0x49 }, { 0x5e, 0x0e },
  { 0x6c, 0x0a }, { 0x6d, 0x55 },
  { 0x6e, 0x11 }, { 0x6f, 0x9e }, /* it was 0x9F "9e for advance AWB" */
  { 0x6a, 0x40 }, { REG_BLUE, 0x40 },
  { REG_RED, 0x60 },
  { REG_COM8, COM8_FASTAEC | COM8_AECSTEP | COM8_AGC | COM8_AEC | COM8_AWB },


  /* Matrix coefficients */

  { 0x4f, 0x80 }, { 0x50, 0x80 },
  { 0x51, 0 },    { 0x52, 0x22 },
  { 0x53, 0x5e }, { 0x54, 0x80 },
  { 0x58, 0x9e },


  { REG_COM16, COM16_AWBGAIN }, { REG_EDGE, 0 },
  { 0x75, 0x05 }, { REG_REG76, 0xe1 },
  { 0x4c, 0 },     { 0x77, 0x01 },
  { REG_COM13, /*0xc3*/0x48 }, { 0x4b, 0x09 },
  { 0xc9, 0x60 },   /*{REG_COM16, 0x38},*/
  { 0x56, 0x40 },


  { 0x34, 0x11 }, { REG_COM11, COM11_EXP | COM11_HZAUTO },
  { 0xa4, 0x82/*Was 0x88*/ }, { 0x96, 0 },
  { 0x97, 0x30 }, { 0x98, 0x20 },
  { 0x99, 0x30 }, { 0x9a, 0x84 },
  { 0x9b, 0x29 }, { 0x9c, 0x03 },
  { 0x9d, 0x4c }, { 0x9e, 0x3f },
  { 0x78, 0x04 },


  /* Extra-weird stuff.  Some sort of multiplexor register */

  { 0x79, 0x01 }, { 0xc8, 0xf0 },
  { 0x79, 0x0f }, { 0xc8, 0x00 },
  { 0x79, 0x10 }, { 0xc8, 0x7e },
  { 0x79, 0x0a }, { 0xc8, 0x80 },
  { 0x79, 0x0b }, { 0xc8, 0x01 },
  { 0x79, 0x0c }, { 0xc8, 0x0f },
  { 0x79, 0x0d }, { 0xc8, 0x20 },
  { 0x79, 0x09 }, { 0xc8, 0x80 },
  { 0x79, 0x02 }, { 0xc8, 0xc0 },
  { 0x79, 0x03 }, { 0xc8, 0x40 },
  { 0x79, 0x05 }, { 0xc8, 0x30 },
  { 0x79, 0x26 },
  { 0xff, 0xff }, /* END MARKER */

};



void error_led(void) {

  VPORTE.DIR |= 32;//make sure led is output uno = DDRB
  while (1) { //wait for reset
    VPORTE.OUT ^= 32;// toggle led uno= PORTB
    _delay_ms(100);

  }

}


void twiStart(void) {

  TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);//send start
  while (!(TWCR & (1 << TWINT)));//wait for start to be transmitted
  if ((TWSR & 0xF8) != TW_START)

    error_led();

}


void twiWriteByte(uint8_t DATA, uint8_t type) {

  TWDR = DATA;
  TWCR = _BV(TWINT) | _BV(TWEN);
  while (!(TWCR & (1 << TWINT))) {}
  if ((TWSR & 0xF8) != type)
    error_led();

}


void twiAddr(uint8_t addr, uint8_t typeTWI) {

  TWDR = addr;//send address
  TWCR = _BV(TWINT) | _BV(TWEN);    /* clear interrupt to start transmission */
  while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
  if ((TWSR & 0xF8) != typeTWI)

    error_led();

}


void writeReg(uint8_t reg, uint8_t dat) {

  //send start condition

  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  twiWriteByte(dat, TW_MT_DATA_ACK);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);

}


static uint8_t twiRd(uint8_t nack) {

  if (nack) {

    TWCR = _BV(TWINT) | _BV(TWEN);
    while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR & 0xF8) != TW_MR_DATA_NACK)
      error_led();
    return TWDR;

  }

  else {

    TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
    while ((TWCR & _BV(TWINT)) == 0); /* wait for transmission */
    if ((TWSR & 0xF8) != TW_MR_DATA_ACK)

      error_led();
    return TWDR;

  }

}


uint8_t rdReg(uint8_t reg) {

  uint8_t dat;

  twiStart();
  twiAddr(camAddr_WR, TW_MT_SLA_ACK);
  twiWriteByte(reg, TW_MT_DATA_ACK);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);
  twiStart();
  twiAddr(camAddr_RD, TW_MR_SLA_ACK);
  dat = twiRd(1);
  TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);//send stop
  _delay_ms(1);
  return dat;

}


void wrSensorRegs8_8(const struct regval_list reglist[]) {

  uint8_t reg_addr, reg_val;
  const struct regval_list *next = reglist;

  while ((reg_addr != 0xff) | (reg_val != 0xff)) {
    reg_addr = pgm_read_byte(&next->reg_num);
    reg_val = pgm_read_byte(&next->value);
    writeReg(reg_addr, reg_val);
    next++;

  }

}


void setColor(void) {

  wrSensorRegs8_8(yuv422_ov7670);
  // wrSensorRegs8_8(qvga_ov7670);

}


void setResolution(void) {

  writeReg(REG_COM3, 4); // REG_COM3 enable scaling
  wrSensorRegs8_8(qvga_ov7670);

}


void camInit(void) {

  writeReg(0x12, 0x80);
  _delay_ms(100);
  wrSensorRegs8_8(ov7670_default_regs);
  writeReg(REG_COM10, 32);//PCLK does not toggle on HBLANK.

}


void arduinoUnoInut(void) {

  cli();//disable interrupts



  /* Setup the 8mhz PWM clock

    This will be on pin 11*/
  VPORTE.DIR |= (1 << 3);//pin 11 //used to be DDRB for uno
  ASSR &= ~(_BV(EXCLK) | _BV(AS2));
  TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);
  TCCR2B = (1 << WGM22) | (1 << CS20);
  OCR2A = 0;//(F_CPU)/(2*(X+1))
  DDRC &= ~15;//low d0-d3 camera
  DDRD &= ~252;//d7-d4 and interrupt pins
  _delay_ms(3000);

  //set up twi for 100khz

  TWSR &= ~3;//disable prescaler for TWI
  TWBR = 72;//set to 100khz

  //enable serial

  UBRR0H = 0;
  UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.
  UCSR0A |= 2;//double speed aysnc
  UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter
  UCSR0C = 6;//async 1 stop bit 8bit char no parity bits

}



void StringPgm(const char * str) {

  do {

    while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
    UDR0 = pgm_read_byte_near(str);
    while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
  } while (pgm_read_byte_near(++str));

}


static void captureImg(uint16_t wg, uint16_t hg) {

  uint16_t y, x;

  StringPgm(PSTR("*RDY*"));

  while (!(PIND & 8));//wait for high
  while ((PIND & 8));//wait for low

  y = hg;

  while (y--) {

    x = wg;

    //while (!(PIND & 256));//wait for high

    while (x--) {

      while ((PIND & 4));//wait for low
      UDR0 = (PINC & 15) | (PIND & 240);
      while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit
      while (!(PIND & 4));//wait for high
      while ((PIND & 4));//wait for low
      while (!(PIND & 4));//wait for high
    }

    //  while ((PIND & 256));//wait for low

  }

  _delay_ms(100);

}


void setup() {

  Wire.begin(); //test
  
  arduinoUnoInut();
  camInit();
  setResolution();
  setColor();
  writeReg(0x11, 10); //Earlier it had the value:writeReg(0x11, 12); 

}



void loop() {

  captureImg(320, 240);

}

Where is the error message pointing

You have a lot of direct references to the hardware registers of the processor (atmega328) in your code. That makes the code very hardware specific, so it is not going to be easily ported to the atmega4809 on the Nano Every, or the SAMD21 on the Nano 33 IOT.

The error is pointing out that there is no TWCR register on the atmega4809.

2 Likes

This is the error message:


Arduino: 1.8.19 (Windows 10), Board: "Arduino Nano Every, None (ATMEGA4809)"





















C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void twiStart()':

noveltest_ov670:510:8: error: 'TWSR' was not declared in this scope

   if ((TWSR & 0xF8) != TW_START)

        ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:510:8: note: suggested alternative: 'TWI0'

   if ((TWSR & 0xF8) != TW_START)

        ^~~~

        TWI0

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void twiWriteByte(uint8_t, uint8_t)':

noveltest_ov670:519:3: error: 'TWDR' was not declared in this scope

   TWDR = DATA;

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:519:3: note: suggested alternative: 'TWI0'

   TWDR = DATA;

   ^~~~

   TWI0

noveltest_ov670:522:8: error: 'TWSR' was not declared in this scope

   if ((TWSR & 0xF8) != type)

        ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:522:8: note: suggested alternative: 'TWI0'

   if ((TWSR & 0xF8) != type)

        ^~~~

        TWI0

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void twiAddr(uint8_t, uint8_t)':

noveltest_ov670:530:3: error: 'TWDR' was not declared in this scope

   TWDR = addr;//send address

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:530:3: note: suggested alternative: 'TWI0'

   TWDR = addr;//send address

   ^~~~

   TWI0

noveltest_ov670:533:8: error: 'TWSR' was not declared in this scope

   if ((TWSR & 0xF8) != typeTWI)

        ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:533:8: note: suggested alternative: 'TWI0'

   if ((TWSR & 0xF8) != typeTWI)

        ^~~~

        TWI0

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'uint8_t twiRd(uint8_t)':

noveltest_ov670:560:10: error: 'TWSR' was not declared in this scope

     if ((TWSR & 0xF8) != TW_MR_DATA_NACK)

          ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:560:10: note: suggested alternative: 'TWI0'

     if ((TWSR & 0xF8) != TW_MR_DATA_NACK)

          ^~~~

          TWI0

noveltest_ov670:562:12: error: 'TWDR' was not declared in this scope

     return TWDR;

            ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:562:12: note: suggested alternative: 'TWI0'

     return TWDR;

            ^~~~

            TWI0

noveltest_ov670:570:10: error: 'TWSR' was not declared in this scope

     if ((TWSR & 0xF8) != TW_MR_DATA_ACK)

          ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:570:10: note: suggested alternative: 'TWI0'

     if ((TWSR & 0xF8) != TW_MR_DATA_ACK)

          ^~~~

          TWI0

noveltest_ov670:573:12: error: 'TWDR' was not declared in this scope

     return TWDR;

            ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:573:12: note: suggested alternative: 'TWI0'

     return TWDR;

            ^~~~

            TWI0

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void arduinoUnoInut()':

noveltest_ov670:651:3: error: 'ASSR' was not declared in this scope

   ASSR &= ~(_BV(EXCLK) | _BV(AS2));

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:651:3: note: suggested alternative: 'SS'

   ASSR &= ~(_BV(EXCLK) | _BV(AS2));

   ^~~~

   SS

In file included from c:\users\gebruiker\appdata\local\arduino15\packages\arduino\tools\avr-gcc\7.3.0-atmel3.6.1-arduino5\avr\include\avr\io.h:99:0,

                 from c:\users\gebruiker\appdata\local\arduino15\packages\arduino\tools\avr-gcc\7.3.0-atmel3.6.1-arduino5\avr\include\avr\pgmspace.h:90,

                 from C:\Users\Gebruiker\AppData\Local\Arduino15\packages\arduino\hardware\megaavr\1.8.7\cores\arduino/api/String.h:31,

                 from C:\Users\Gebruiker\AppData\Local\Arduino15\packages\arduino\hardware\megaavr\1.8.7\cores\arduino/api/IPAddress.h:24,

                 from C:\Users\Gebruiker\AppData\Local\Arduino15\packages\arduino\hardware\megaavr\1.8.7\cores\arduino/api/ArduinoAPI.h:30,

                 from C:\Users\Gebruiker\AppData\Local\Arduino15\packages\arduino\hardware\megaavr\1.8.7\cores\arduino/Arduino.h:23,

                 from sketch\noveltest_ov670.ino.cpp:1:

noveltest_ov670:651:17: error: 'EXCLK' was not declared in this scope

   ASSR &= ~(_BV(EXCLK) | _BV(AS2));

                 ^

noveltest_ov670:651:30: error: 'AS2' was not declared in this scope

   ASSR &= ~(_BV(EXCLK) | _BV(AS2));

                              ^

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:651:30: note: suggested alternative: 'A2'

noveltest_ov670:652:3: error: 'TCCR2A' was not declared in this scope

   TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);

   ^~~~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:652:3: note: suggested alternative: 'TCB2'

   TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);

   ^~~~~~

   TCB2

noveltest_ov670:652:18: error: 'COM2A0' was not declared in this scope

   TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);

                  ^~~~~~

noveltest_ov670:652:34: error: 'WGM21' was not declared in this scope

   TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);

                                  ^~~~~

noveltest_ov670:652:49: error: 'WGM20' was not declared in this scope

   TCCR2A = (1 << COM2A0) | (1 << WGM21) | (1 << WGM20);

                                                 ^~~~~

noveltest_ov670:653:3: error: 'TCCR2B' was not declared in this scope

   TCCR2B = (1 << WGM22) | (1 << CS20);

   ^~~~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:653:3: note: suggested alternative: 'TCB2'

   TCCR2B = (1 << WGM22) | (1 << CS20);

   ^~~~~~

   TCB2

noveltest_ov670:653:18: error: 'WGM22' was not declared in this scope

   TCCR2B = (1 << WGM22) | (1 << CS20);

                  ^~~~~

noveltest_ov670:653:33: error: 'CS20' was not declared in this scope

   TCCR2B = (1 << WGM22) | (1 << CS20);

                                 ^~~~

noveltest_ov670:654:3: error: 'OCR2A' was not declared in this scope

   OCR2A = 0;//(F_CPU)/(2*(X+1))

   ^~~~~

noveltest_ov670:655:3: error: 'DDRC' was not declared in this scope

   DDRC &= ~15;//low d0-d3 camera

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:655:3: note: suggested alternative: 'DD0'

   DDRC &= ~15;//low d0-d3 camera

   ^~~~

   DD0

noveltest_ov670:656:3: error: 'DDRD' was not declared in this scope

   DDRD &= ~252;//d7-d4 and interrupt pins

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:656:3: note: suggested alternative: 'VDD'

   DDRD &= ~252;//d7-d4 and interrupt pins

   ^~~~

   VDD

noveltest_ov670:661:3: error: 'TWSR' was not declared in this scope

   TWSR &= ~3;//disable prescaler for TWI

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:661:3: note: suggested alternative: 'TWI0'

   TWSR &= ~3;//disable prescaler for TWI

   ^~~~

   TWI0

noveltest_ov670:662:3: error: 'TWBR' was not declared in this scope

   TWBR = 72;//set to 100khz

   ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:662:3: note: suggested alternative: 'TWI0'

   TWBR = 72;//set to 100khz

   ^~~~

   TWI0

noveltest_ov670:666:3: error: 'UBRR0H' was not declared in this scope

   UBRR0H = 0;

   ^~~~~~

noveltest_ov670:667:3: error: 'UBRR0L' was not declared in this scope

   UBRR0L = 1;//0 = 2M baud rate. 1 = 1M baud. 3 = 0.5M. 7 = 250k 207 is 9600 baud rate.

   ^~~~~~

noveltest_ov670:668:3: error: 'UCSR0A' was not declared in this scope

   UCSR0A |= 2;//double speed aysnc

   ^~~~~~

noveltest_ov670:669:3: error: 'UCSR0B' was not declared in this scope

   UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter

   ^~~~~~

noveltest_ov670:669:18: error: 'RXEN0' was not declared in this scope

   UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter

                  ^~~~~

noveltest_ov670:669:33: error: 'TXEN0' was not declared in this scope

   UCSR0B = (1 << RXEN0) | (1 << TXEN0);//Enable receiver and transmitter

                                 ^~~~~

noveltest_ov670:670:3: error: 'UCSR0C' was not declared in this scope

   UCSR0C = 6;//async 1 stop bit 8bit char no parity bits

   ^~~~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void StringPgm(const char*)':

noveltest_ov670:680:14: error: 'UCSR0A' was not declared in this scope

     while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

              ^~~~~~

noveltest_ov670:680:29: error: 'UDRE0' was not declared in this scope

     while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

                             ^~~~~

noveltest_ov670:681:5: error: 'UDR0' was not declared in this scope

     UDR0 = pgm_read_byte_near(str);

     ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:681:5: note: suggested alternative: 'ADC0'

     UDR0 = pgm_read_byte_near(str);

     ^~~~

     ADC0

noveltest_ov670:682:14: error: 'UCSR0A' was not declared in this scope

     while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

              ^~~~~~

noveltest_ov670:682:29: error: 'UDRE0' was not declared in this scope

     while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

                             ^~~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void captureImg(uint16_t, uint16_t)':

noveltest_ov670:694:12: error: 'PIND' was not declared in this scope

   while (!(PIND & 8));//wait for high

            ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:694:12: note: suggested alternative: 'PIN0'

   while (!(PIND & 8));//wait for high

            ^~~~

            PIN0

noveltest_ov670:695:11: error: 'PIND' was not declared in this scope

   while ((PIND & 8));//wait for low

           ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:695:11: note: suggested alternative: 'PIN0'

   while ((PIND & 8));//wait for low

           ^~~~

           PIN0

noveltest_ov670:707:15: error: 'PIND' was not declared in this scope

       while ((PIND & 4));//wait for low

               ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:707:15: note: suggested alternative: 'PIN0'

       while ((PIND & 4));//wait for low

               ^~~~

               PIN0

noveltest_ov670:708:7: error: 'UDR0' was not declared in this scope

       UDR0 = (PINC & 15) | (PIND & 240);

       ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:708:7: note: suggested alternative: 'ADC0'

       UDR0 = (PINC & 15) | (PIND & 240);

       ^~~~

       ADC0

noveltest_ov670:708:15: error: 'PINC' was not declared in this scope

       UDR0 = (PINC & 15) | (PIND & 240);

               ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:708:15: note: suggested alternative: 'PIN0'

       UDR0 = (PINC & 15) | (PIND & 240);

               ^~~~

               PIN0

noveltest_ov670:708:29: error: 'PIND' was not declared in this scope

       UDR0 = (PINC & 15) | (PIND & 240);

                             ^~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino:708:29: note: suggested alternative: 'PIN0'

       UDR0 = (PINC & 15) | (PIND & 240);

                             ^~~~

                             PIN0

noveltest_ov670:709:16: error: 'UCSR0A' was not declared in this scope

       while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

                ^~~~~~

noveltest_ov670:709:31: error: 'UDRE0' was not declared in this scope

       while (!(UCSR0A & (1 << UDRE0)));//wait for byte to transmit

                               ^~~~~

C:\Users\Gebruiker\Documents\Arduino\noveltest_ov670\noveltest_ov670.ino: In function 'void setup()':

noveltest_ov670:726:3: error: 'Wire' was not declared in this scope

   Wire.begin(); //test

   ^~~~

exit status 1

'TWSR' was not declared in this scope

Okay, that sounds right where the problem is. But How can you write a code/library without those hardware specific codes? Or better how to "translate" it. Because if there is not TWI control register in the atmega328 then the whole logic needs to be rewritten (?). So basically I want to handle the problem, instead of chosing diffrent hardware, and learn how to write it but don't know where to start.

The Nano Every uses an atmega4809, not an atmega328. Both have TWI control registers, but they use different naming conventions and are not organized the same. You will need to consult the data sheet for the atmega4809 to see what the equivalent hardware references are.

As for making the library usable with different processor architectures, you will need to include code for each specific processor type, and make it conditional on the processor the code is being compiled for.

1 Like

Yes I meant the atmega 4809 instead of the 328 I wrote. Okay so in anyway I need a selection of processor and based on that a different naming of everything. So I could 'just' strugle to the 300 pages datasheet and will find the exact translation to the registers? because I started this but didn't find anything for TWCR (will continue looking later today).
Thanks for clearing things up already!

Where did you find that code ?
If you want that code to work, then you should buy a board with a ATmega328P microcontroller.

The Arduino has functions and libraries that should do the same for every Arduino board. If you have code that does not use Arduino functions, but use direct register access, then it will only work for that board.

Can you explain why you're doing it the hard way? Except that it can be fun to learn :wink:

Arduino comes with the Wire library that provides the abstraction layer. So any code using the Wire library should not pose a problem.

Well not 300 pages, just the relevant ones. There probably won't be a like for like change of register name because the hardware probably functions differently, in which case you have to rewrite to match the hardware requirements.

True, I want it to work on a smaller microcontrol and decided to use the arduino nano every.

Well, first to learn and to not be depended on code found on the internet (or at least know what I use). And because I did not found any examples on the arduino uno every, most examples of sensors are on the uno anyway, but until now I didn't realize the issue in using different arduino products.

My plan B is building the code with wire.h as a tool, but that seemed like the longer solution. However that maybe the simpeler solution....

Yes only the relevant ones! But ctrl-F didnot provide with a quick answer so will need some time to find in the 25 or so pages on TWI.
So no direct translation possible, well better read those sections well to understand the logic difference then. Any suggestion on making this easier are welcome! (or tips or so...)

The wire library is part of the core so you will only depend on Arduino, not the internet :wink:

It's actually the shorter / fasster solution. The cores for both the AVR and megaAVR have their own Wire library; under the hood, they make use of their own TWI code.

1 Like

Yes I'm beginning to come to the same conclusion will persue your idea and see how far I come!
Thanks!

Either by using generic code that uses standard C++/Arduino functions or by having the library test the processor type being used and invoking different code that accesses registers depending on the processor

Speed of execution is the usual reason for using registers directly rather than functions, but that implies that a library will be updated to support different processor types as they become available but this is often not done

1 Like

In the short term, if you want the small footprint of a nano, use the atmega328 based nano and the code should run without modification.

2 Likes

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