(See the README.md file in the upper level 'examples' directory for more information about examples.)
This example demonstrates basic usage of I2C driver by running two tasks on I2C bus:
If you have a new I2C application to go (for example, read the temperature data from external sensor with I2C interface), try this as a basic template, then add your own code.
To run this example, you should have one ESP32 dev board (e.g. ESP32-WROVER Kit) or ESP32 core board (e.g. ESP32-DevKitC). Optionally, you can also connect an external sensor, here we choose the BH1750 just for an example. BH1750 is a digital ambient light sensor, for more information about it, you can read the PDF of this sensor.
Note: The following pin assignments are used by default, yout can change these in the menuconfig
.
SDA | SCL | |
---|---|---|
ESP32 I2C Master | GPIO18 | GPIO19 |
ESP32 I2C Slave | GPIO25 | GPIO26 |
BH1750 Sensor | SDA | SCL |
slave:
master:
Connection:
Note: There’s no need to add an external pull-up resistors for SDA/SCL pin, because the driver will enable the internal pull-up resistors.
Open the project configuration menu (idf.py menuconfig
). Then go into Example Configuration
menu.
I2C Master
submenu, you can set the pin number of SDA/SCL according to your board. Also you can modify the I2C port number and freauency of the master.I2C Slave
submenu, you can set the pin number of SDA/SCL according to your board. Also you can modify the I2C port number and address of the slave.BH1750 Sensor
submenu, you can choose the slave address of BH1750 accroding to the pin level of ADDR pin (if the pin level of ADDR is low then the address is 0x23
, otherwise it is 0x5c
). Here you can also control the operation mode of BH1750, each mode has a different resolution and measurement time. For example, in the One Time L-Resolution
mode, the resolution is 4 Lux and measurement time is typically 16ms (higher resolution means longer measurement time). For more information, you can consult the datasheet of BH1750.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 for full steps to configure and use ESP-IDF to build projects.
I (6495) i2c-example: TASK[1] test cnt: 1
*******************
TASK[1] MASTER READ SENSOR( BH1750 )
*******************
data_h: 01
data_l: d0
sensor val: 386.67 [Lux]
I (6695) i2c-example: TASK[0] test cnt: 2
*******************
TASK[0] MASTER READ SENSOR( BH1750 )
*******************
data_h: 01
data_l: d0
sensor val: 386.67 [Lux]
*******************
TASK[0] MASTER READ FROM SLAVE
*******************
====TASK[0] Slave buffer data ====
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
====TASK[0] Master read ====
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
*******************
TASK[1] MASTER READ FROM SLAVE
*******************
====TASK[1] Slave buffer data ====
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
====TASK[1] Master read ====
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
*******************
TASK[0] MASTER WRITE TO SLAVE
*******************
----TASK[0] Master write ----
0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19
1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 29
2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39
3a 3b 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 49
4a 4b 4c 4d 4e 4f 50 51 52 53 54 55 56 57 58 59
5a 5b 5c 5d 5e 5f 60 61 62 63 64 65 66 67 68 69
6a 6b 6c 6d 6e 6f 70 71 72 73 74 75 76 77 78 79
7a 7b 7c 7d 7e 7f 80 81 82 83 84 85 86 87 88 89
----TASK[0] Slave read: [128] bytes ----
0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19
1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 29
2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37 38 39
3a 3b 3c 3d 3e 3f 40 41 42 43 44 45 46 47 48 49
4a 4b 4c 4d 4e 4f 50 51 52 53 54 55 56 57 58 59
5a 5b 5c 5d 5e 5f 60 61 62 63 64 65 66 67 68 69
6a 6b 6c 6d 6e 6f 70 71 72 73 74 75 76 77 78 79
7a 7b 7c 7d 7e 7f 80 81 82 83 84 85 86 87 88 89
ADDR
pin at start up. Make sure to check your schemetic before run this example.(For any technical queries, please open an issue on GitHub. We will get back to you as soon as possible.)