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.
| left side pin | via | right side pin |
|---|---|---|
| (bit8) GPBO | 10KOhm | GPA7 (bit7) |
| (bit9) GPB1 | 10KOhm | GPA6 (bit6) |
| (bit10) GPB2 | 10KOhm | GPA5 (bit5) |
| (bit11) GPB3 | 10KOhm | GPA4 (bit4) |
| (bit12) GPB4 | 10KOhm | GPA3 (bit3) |
| (bit13) GPB5 | 10KOhm | GPA2 (bit2) |
| (bit14) GPB6 | 10KOhm | GPA1 (bit1) |
| (bit15) GPB7 | 10KOhm | GPA0 (bit0) |
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)