This test demonstrates basic usage of I2C driver with wifi softAP.
### I2C MASTER
1. Switch on wifi softAP, and connect to your personal device, like your mobile phone.
2. Send data to slave board.
### I2C SLAVE
1. Receive data from master board.
## How to use test
### Hardware Required
To run this test, you should have at least one ESP development board for master. But to make this test convenient, we also use a ESP development board for slave. (You can change your slave device, but don't forget to change code as well if necessary.)
#### Pin Assignment
**Note:** The following pin assignments are used by default, you can change these in the `menuconfig` .
| | SDA | SCL |
| ------------------ | ------ | ------ |
| ESP32/ESP32-S2 I2C | GPIO18 | GPIO19 |
| ESP32-S3 I2C | GPIO1 | GPIO2 |
| ESP32-C3 I2C | GPIO5 | GPIO9 |
**Note:** It is recommended to add external pull-up resistors for SDA/SCL pins to make the communication more stable, though the driver will enable internal pull-up resistors.
### Configure the project
Open the project configuration menu (`idf.py menuconfig`). Then go into `Test Configuration` menu.
#### I2C MASTER configuration
- In the `I2C working mode select` menu, you can set the working mode of i2c, choose `i2c master mode`.
- In the `I2C Configuration` menu, you can set the pin number of SDA/SCL. Also you can modify the I2C port number and frequency of the master. And you can set the slave address here as well.
- Enable `WIFI AP` if you need it.
- In the `WIFI softAP Configuration` menu, you can set the wifi information here.
#### I2C SLAVE configuration
- In the `I2C working mode select` menu, you can set the working mode of i2c, choose `i2c slave mode`.
- In the `I2C Configuration` menu, you can set the pin number of SDA/SCL. Also you can modify the I2C port number and address of the slave.
### Build and Flash
Enter `idf.py -p PORT flash monitor` to build, flash and monitor the project.
(To exit the serial monitor, type ``Ctrl-]``.)
See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
## Test Output
### MASTER
```bash
I (339) cpu_start: Starting scheduler.
I (359) I2C-wifi test: ESP_WIFI_MODE_AP
I (359) pp: pp rom version: 9387209
I (359) net80211: net80211 rom version: 9387209
I (369) wifi:wifi driver task: 3fc9def0, prio:23, stack:6656, core=0
I (369) system_api: Base MAC address is not set
I (379) system_api: read default base MAC address from EFUSE
I (379) wifi:wifi firmware version: d062fdb
I (389) wifi:wifi certification version: v7.0
I (389) wifi:config NVS flash: enabled
I (389) wifi:config nano formating: disabled
I (399) wifi:Init data frame dynamic rx buffer num: 32
I (399) wifi:Init management frame dynamic rx buffer num: 32
I (409) wifi:Init management short buffer num: 32
I (409) wifi:Init dynamic tx buffer num: 32
I (419) wifi:Init static tx FG buffer num: 2
I (419) wifi:Init static rx buffer size: 1600
I (419) wifi:Init static rx buffer num: 10
I (429) wifi:Init dynamic rx buffer num: 32
I (429) wifi_init: rx ba win: 6
I (439) wifi_init: tcpip mbox: 32
I (439) wifi_init: udp mbox: 6
I (439) wifi_init: tcp mbox: 6
I (449) wifi_init: tcp tx win: 5744
I (449) wifi_init: tcp rx win: 5744
I (459) wifi_init: tcp mss: 1440
I (459) wifi_init: WiFi IRAM OP enabled
I (459) wifi_init: WiFi RX IRAM OP enabled
I (469) phy_init: phy_version 500,985899c,Apr 19 2021,16:05:08
I (589) wifi:set rx active PTI: 0, rx ack PTI: 0, and default PTI: 0
I (599) wifi:mode : softAP (7c:df:a1:86:d8:a9)
I (599) wifi:Total power save buffer number: 16
I (599) wifi:Init max length of beacon: 752/752
I (599) wifi:Init max length of beacon: 752/752
I (609) I2C-wifi test: wifi_init_softap finished. SSID:myssid password:mypassword channel:1
