On the Teensy 3.1, where are the I2C pins (SDA, SCL) located?
I ~thought~ it was pin 18 & 19.
I loaded the code below. I have (2) 4.7k resistors on the I2C inputs on my MCP23008.
When I put my scope on SDA or SCL, there is no transmission, just 3.3V steady.
#include <Wire.h>
void setup() {
Wire.begin(); // initialise the wire library and hardware
Wire.beginTransmission(0x40); // start talking to the device
Wire.send(0x00); // select the IODIR register
Wire.send(0xff); // set register value-all high, sets all pins as outputs on MCP23008
Wire.endTransmission(); // stop talking to the devicevice
pinMode(13, OUTPUT);
}
void loop() {
Wire.beginTransmission(0x40); // start talking to the device
Wire.send(0x09); // select the GPIO register
Wire.send(0xff); // set register value-all high
Wire.endTransmission(); // stop talking to the device
digitalWrite(13, LOW);
delay(500); // wait for 1/2 a second
Wire.begin(); // initialise the wire library and hardware
Wire.beginTransmission(0x40); // start talking to the device
Wire.send(0x09); // select the GPIO register
Wire.send(0x00); // set register value-all low
Wire.endTransmission(); // stop talking to the device
digitalWrite(13, HIGH);
delay(500); // wait for 1/2 a second
}