Hello! I think I may have found a bug in Wire.cpp, though it could be a mistake on my end- after debugging and a slight modification to Wire.cpp it seems to fix the issue.
I am using a large amount of RAM on the Teensy 3.1 and when trying to use the Wire library with Adafruit_MCP23017 the Teensy hangs. Interestingly I'm using the up to date Platformio for compilation, and when testing in the Arduino IDE, it works fine. Even ended up copying over the Teensy Library files to make sure everything matched between Platformio and Arduino.
The issue seems to be from the TwoWire::requestFrom method:
When I add in a condition to the count variable via "if(count >= BUFFER_LENGTH) count = 0;" before writing to rxBuffer everything works as expected. Though looking at it there is no reason for count to get so high that it overflows. Since it doesn't happen in the Arduino IDE, I suspect something strange is happening when the code is compiled in Platformio. (Different version of GCC? No idea.)
Here is the test code I was working with:
I am using a large amount of RAM on the Teensy 3.1 and when trying to use the Wire library with Adafruit_MCP23017 the Teensy hangs. Interestingly I'm using the up to date Platformio for compilation, and when testing in the Arduino IDE, it works fine. Even ended up copying over the Teensy Library files to make sure everything matched between Platformio and Arduino.
The issue seems to be from the TwoWire::requestFrom method:
Code:
while (length > 1) {
i2c_wait();
length--;
if (length == 1) I2C0_C1 = I2C_C1_IICEN | I2C_C1_MST | I2C_C1_TXAK;
rxBuffer[count++] = I2C0_D;
}
i2c_wait();
I2C0_C1 = I2C_C1_IICEN | I2C_C1_MST | I2C_C1_TX;
rxBuffer[count++] = I2C0_D;
if (sendStop) I2C0_C1 = I2C_C1_IICEN;
rxBufferLength = count;
return count;When I add in a condition to the count variable via "if(count >= BUFFER_LENGTH) count = 0;" before writing to rxBuffer everything works as expected. Though looking at it there is no reason for count to get so high that it overflows. Since it doesn't happen in the Arduino IDE, I suspect something strange is happening when the code is compiled in Platformio. (Different version of GCC? No idea.)
Here is the test code I was working with:
Code:
#include <Wire.h>
#include "Adafruit_MCP23017.h"
Adafruit_MCP23017 mcp;
uint8_t some_big_data[50000];
void setup() {
pinMode(13,OUTPUT);
digitalWrite(13, HIGH);
delay(300);
digitalWrite(13, LOW);
delay(300);
Serial1.begin(9600);
Serial1.println(some_big_data[0]);
mcp.begin();
mcp.pinMode(0, INPUT);
mcp.pullUp(0, HIGH);
mcp.pinMode(1, INPUT);
mcp.pullUp(1, HIGH);
}
void loop() {
digitalWrite(13, LOW);
delay(300);
digitalWrite(13, HIGH);
delay(300);
}
Unfortunately the Arduino IDE is pretty tedious for large projects. Gah!