I'm not sure if this is the right place to post this, but here goes: Basically what I'm trying to do is use the ArduCAM OV2640 Camera module to take a picture then save it to a microSD card. The only problem is that I don't fully understand how SPI works. I barely understand the concepts of MOSI, MISO, SCK, and CS.
This is the code I'm using, taken from ArduCAM:
#include <ArduCAM.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include "memorysaver.h"
//This demo can only work on OV2640_MINI_2MP or OV5642_MINI_5MP or OV5642_MINI_5MP_BIT_ROTATION_FIXED platform.
#if !(defined OV5642_MINI_5MP || defined OV5642_MINI_5MP_BIT_ROTATION_FIXED || defined OV2640_MINI_2MP || defined OV3640_MINI_3MP)
#error Please select the hardware platform and camera module in the ../libraries/ArduCAM/memorysaver.h file
#endif
#define SD_CS 9
const int SPI_CS = 10;
#if defined (OV2640_MINI_2MP)
ArduCAM myCAM( OV2640, SPI_CS );
#elif defined (OV3640_MINI_3MP)
ArduCAM myCAM( OV3640, SPI_CS );
#else
ArduCAM myCAM( OV5642, SPI_CS );
#endif
void myCAMSaveToSDFile(){
char str[8];
byte buf[256];
static int i = 0;
static int k = 0;
uint8_t temp = 0,temp_last=0;
uint32_t length = 0;
bool is_header = false;
File outFile;
//Flush the FIFO
myCAM.flush_fifo();
//Clear the capture done flag
myCAM.clear_fifo_flag();
//Start capture
myCAM.start_capture();
Serial.println(F("start Capture"));
while(!myCAM.get_bit(ARDUCHIP_TRIG , CAP_DONE_MASK));
Serial.println(F("Capture Done."));
length = myCAM.read_fifo_length();
Serial.print(F("The fifo length is :"));
Serial.println(length, DEC);
if (length >= MAX_FIFO_SIZE) //384K
{
Serial.println(F("Over size."));
return ;
}
if (length == 0 ) //0 kb
{
Serial.println(F("Size is 0."));
return ;
}
//Construct a file name
k = k + 1;
itoa(k, str, 10);
strcat(str, ".jpg");
//Open the new file
outFile = SD.open(str, O_WRITE | O_CREAT | O_TRUNC);
if(!outFile){
Serial.println(F("File open faild"));
return;
}
myCAM.CS_LOW();
myCAM.set_fifo_burst();
while ( length-- )
{
temp_last = temp;
temp = SPI.transfer(0x00);
//Read JPEG data from FIFO
if ( (temp == 0xD9) && (temp_last == 0xFF) ) //If find the end ,break while,
{
buf[i++] = temp; //save the last 0XD9
//Write the remain bytes in the buffer
myCAM.CS_HIGH();
outFile.write(buf, i);
//Close the file
outFile.close();
Serial.println(F("Image save OK."));
is_header = false;
i = 0;
}
if (is_header == true)
{
//Write image data to buffer if not full
if (i < 256)
buf[i++] = temp;
else
{
//Write 256 bytes image data to file
myCAM.CS_HIGH();
outFile.write(buf, 256);
i = 0;
buf[i++] = temp;
myCAM.CS_LOW();
myCAM.set_fifo_burst();
}
}
else if ((temp == 0xD8) & (temp_last == 0xFF))
{
is_header = true;
buf[i++] = temp_last;
buf[i++] = temp;
}
}
}
void setup(){
uint8_t vid, pid;
uint8_t temp;
Wire.begin();
Serial.begin(115200);
Serial.println(F("ArduCAM Start!"));
//set the CS as an output:
pinMode(SPI_CS,OUTPUT);
pinMode(7, OUTPUT);
// initialize SPI:
SPI.begin();
while(1){
//Check if the ArduCAM SPI bus is OK
myCAM.write_reg(ARDUCHIP_TEST1, 0x55);
temp = myCAM.read_reg(ARDUCHIP_TEST1);
if (temp != 0x55){
Serial.println(F("SPI interface Error!"));
delay(1000);continue;
}else{
Serial.println(F("SPI interface OK."));break;
}
}
//Initialize SD Card
while(!SD.begin(SD_CS)){
Serial.println(F("SD Card Error!"));delay(1000);
}
Serial.println(F("SD Card detected."));
#if defined (OV2640_MINI_2MP)
while(1){
//Check if the camera module type is OV2640
myCAM.wrSensorReg8_8(0xff, 0x01);
myCAM.rdSensorReg8_8(OV2640_CHIPID_HIGH, &vid);
myCAM.rdSensorReg8_8(OV2640_CHIPID_LOW, &pid);
if ((vid != 0x26 ) && (( pid != 0x41 ) || ( pid != 0x42 ))){
Serial.println(F("Can't find OV2640 module!"));
delay(1000);continue;
}
else{
Serial.println(F("OV2640 detected."));break;
}
}
#elif defined (OV3640_MINI_3MP)
while(1){
//Check if the camera module type is OV3640
myCAM.rdSensorReg16_8(OV3640_CHIPID_HIGH, &vid);
myCAM.rdSensorReg16_8(OV3640_CHIPID_LOW, &pid);
if ((vid != 0x36) || (pid != 0x4C)){
Serial.println(F("Can't find OV3640 module!"));
delay(1000);continue;
}else{
Serial.println(F("OV3640 detected."));break;
}
}
#else
while(1){
//Check if the camera module type is OV5642
myCAM.wrSensorReg16_8(0xff, 0x01);
myCAM.rdSensorReg16_8(OV5642_CHIPID_HIGH, &vid);
myCAM.rdSensorReg16_8(OV5642_CHIPID_LOW, &pid);
if((vid != 0x56) || (pid != 0x42)){
Serial.println(F("Can't find OV5642 module!"));
delay(1000);continue;
}
else{
Serial.println(F("OV5642 detected."));break;
}
}
#endif
myCAM.set_format(JPEG);
myCAM.InitCAM();
#if defined (OV2640_MINI_2MP)
myCAM.OV2640_set_JPEG_size(OV2640_320x240);
#elif defined (OV3640_MINI_3MP)
myCAM.OV3640_set_JPEG_size(OV3640_320x240);
#else
myCAM.write_reg(ARDUCHIP_TIM, VSYNC_LEVEL_MASK); //VSYNC is active HIGH
myCAM.OV5642_set_JPEG_size(OV5642_320x240);
#endif
delay(1000);
}
void loop(){
myCAMSaveToSDFile();
delay(5000);
}
The main thing that's giving me a problem is this beginning of the setup code. I currently have both the sd card module and arducam wired up to MOSI on pin 11 of my Arduino UNO R3. However when I run the code like this I get an SPI interface error. When I unplug the MOSI pin of the sd card module, it no longer results in an SPI error and the camera works (however the sd card doesn't).
I did some research and looked at issues on the ArduCAM github. Someone suggested that certain SD card modules don't allow for SPI bus sharing / prevent other devices from using SPI? This is the sd card module that I'm using.
As for wiring, I just wired the sd card module to the MISO/MOSI/SCK pins for the Arduino UNO R3, and used the CS pin defined in the code. For the camera I followed this schematic (and modified CS pin)
Any help would be greatly appreciated.