I²C Port expander driver example for esp8266. It connects to the mcp2307 with two GPIO pins of your own choice.

The API is very arduino:like, here is the mandatory blinky example:

#include "mcp23017/mcp23017.h"
....
// setup
MCP23017_Self mcpSelf;  // in lieu of C++ member data we have structs :)
uint8_t deviceAddr=0;
uint8_t aMcpPin = 2; // the pin on the mcp23017 we want to write to
i2c_master_gpio_init(); // uses the pins defined by I2C_MASTER_SDA_GPIO & I2C_MASTER_SCL_GPIO
i2c_master_init();  
mcp23017_init(&mcpSelf);
mcp23017_pinMode(&mcpSelf, deviceAddr, aMcpPin, MCP23017_OUTPUT);

....

// loop
mcp23017_digitalWrite(&mcpSelf, deviceAddr, aMcpPin, 0);
delay
mcp23017_digitalWrite(&mcpSelf, deviceAddr, aMcpPin, 1);
delay

You can access the bits one by one like above, by whole bytes or all the bits at once (uint16_t).

The I²C driver is an extended version of the IoT demo i2c_master driver.

While the rest of the MCP23017 driver is a heavily modified port of Adafruit-MCP23017-Arduino-Library.

• interrupt support. I don't need this so it won't happend unless someone requests it.

I've added a very basic, basic test into the demo. To use this test you should connect each output pin of the mcp23017 to corresponding pin on the 'other side' via a 10+K resistor.

Hopefully you should see the text all tests passed in the console.

GNU GENERAL PUBLIC LICENSE Version 3

The makefile is copied from esp_mqtt.

###Building and installing:

First you need to install the sdk and the easy way of doing that is to use esp_open_sdk.

You can put that anywhere you like (/opt/local/esp-open-sdk, /esptools etc etc)

Then you could create a small setenv.sh file, containing the location of your newly compiled sdk and other platform specific info;

export SDK_BASE=/opt/local/esp-open-sdk/sdk
export PATH=${SDK_BASE}/../xtensa-lx106-elf/bin:${PATH}
export ESPPORT=/dev/ttyO0  

(or setup your IDE to do the same)

To make a clean build, flash and connect to the esp console you just do this in a shell:

source setenv.sh # This is only needed once per session
make clean && make test

You won't be needing esptool, the makefile only uses esptool.py (provided by esp_open_sdk)

I have tested this with sdk v0.9.5 and v0.9.4 (linux & mac)