I am interested in moving from the Nano to an ATMega328-AU (32 pin TQFP) on a PCB. I have the PCB made (w/16mhz xtal) and can upload the bootloader via USBtinyISP. I can upload the example Blink sketch via FTDI w/o issue. So the communication between IDE and my PCB is fine.
My problem arises with the pin mapping. It appears if I define a pin in the sketch it correlates to a pin on the Nano board (not the uP). For example, if I #define LED 19
That refers to pin 19 on the Nano Board, which is pin 28 on the Atmega. That ripples down to every other pin being misleading, like SPI pins. Serial.println(MOSI); reports 11 ... again, pin 11 on the Nano, which routes to pin 16 on the uP.
So a simple SPI.begin() will not be using the MOSI associated with the uP.
More than likely there's something I overlooked or something stupid altogether. Is there a way to use the uP pins instead of the Arduino board pins?
MOSI on the ATMega is pin 17 on the chip, PB3, Digital IO pin 11. If you define a pin in the (IDE) sketch and you are looking for the pin on the chip, you need to compare the Digital pin number to a pinout diagram and locate which physical chip pin relates to that Arduino definition of the IO pin in software.
To look at your example of LED19 - the IDE interprets 19 as Analog5, SCL, specifically pin 28 on the chip. To help sort this out, try this:
The internal LED is on D13 according to the IDE. D13 appears on the NANO on connector 16. D13 refers to the the physical ATMEGA pin 19, which is used for PB5, PCINT5 and SCK as well as the LED. Use the NANO pinout diagram and the ATMEGA pinout diagram to make the links you need.
Thanks for the reply.
First, I clearly stated this was TQFP, so MOSI on the Atmega is pin 15 (see attached pic of TQFP). But that's irrelevant.
I get what you're saying. But there must be a way that I don't need a secret decoder ring to figure out which pin I want to access on the Atmega. I created this (decoder ring) inside my sketch..
// Nano dec port ATMega328-AU Nano dec port ATMega328-AU
// ------------- -------------------- ------------- -------------------
// pin (12) D12 -> IC pin 16 (MISO) pin (13) D13 -> IC pin 17 (SCK)
// pin (11) D11 -> IC pin 15 (MOSI) pin 3.3V
// pin (10) D10 -> IC pin 14 (PB2) pin AREF -> IC pin 20 (AREF)
// pin ( 9) D09 -> IC pin 13 (PB1) pin (14) PC0 -> IC pin 23 (PC0/ADC0)
// pin ( 8) D08 -> IC pin 12 (PB0) pin (15) PC1 -> IC pin 24 (PC1/ADC1)
// pin ( 7) D07 -> IC pin 11 (PD7) pin (16) PC2 -> IC pin 25 (PC2/ADC2)
// pin ( 6) D06 -> IC pin 10 (PD6) pin (17) PC3 -> IC pin 26 (PC3/ADC3)
// pin ( 5) D05 -> IC pin 09 (PD5) pin (18) PC4 -> IC pin 27 (PC4/ADC4)
// pin ( 4) D04 -> IC pin 02 (PD4) pin (19) PC5 -> IC pin 28 (PC5/ADC5)
// pin ( 3) D03 -> IC pin 01 (PD3) pin (??) ADC6 -> IC pin 19 (ADC6)
// pin ( 2) D02 -> IC pin 32 (PD2/INT0) pin (??) ADC7 -> IC pin 22 (ADC7)
// pin (??) RST -> IC pin 29 (PC6/RESET) pin (??) PC6 -> IC pin 29 (RESET/PC6)
// pin (??) RXD -> IC pin 30 (RX/PD0) pin GND
// pin (??) TXD -> IC pin 31 (TX/PD1) pin VIN
// --- --- -> IC pin 08 (PB7/OSC2) --- --- -> IC pin 07 (PB8/OSC1)
// --- --- -> IC pin 03/05/21 (GND) --- --- -> IC pin 04/06/18 (VCC/VCC/AVCC)
Going back to an example; LED_BUILTIN is defined as 13 (IC pin 17) but my PCB has it on IC pin 28. I don't want to look up what pin on the Arduino (19) maps to IC pin 28, I just want to call/reference pin 28.
I have created my own variant of pins_arduino.h and can kind of fake it by defining my own names (#define MY_LED_BUILTIN (19) ) , which does not solve my underlying question but does make programming easier .. until you print what MY_LED_BUILTIN is, and 19 is NOT what I'd expect.
So, is there no way to redefine pin names to Atmega pins ??
There has to be since different Arduino boards have different pinouts/IC's (Mega vs Nano .. DIP vs TQFP, etc)
I guess I just need guidance on creating my own board, etc. Not asking anyone here to do it, just point me to the docs that explain how (and maybe any gotcha's to watch out for).
