TWI AT commands

This page describes AT commands related to the Two-Wire Interface (TWI).

List TWI instances #XTWILS 

The #XTWILS command lists all available TWI instances.

Set command 

The set command allows you to list all available TWI instances.

Response syntax

#XTWILS: <index>[[[,<index>],<index>],<index>]

The <index> parameter corresponds to the following TWI instances:

0 - TWI0 (i2c0).
1 - TWI1 (i2c1).
2 - TWI2 (i2c2).
3 - TWI3 (i2c3).

See nordic,nrf-twi.

Example

The following example is meant for Thingy:91.

It shows that TWI2 (i2c2) is available.

AT#XTWILS
#XTWILS: 2
OK

Read command 

The read command is not supported.

Test command 

The test command is not supported.

Write to TWI peripheral device #XTWIW 

The #XTWIW command writes data to a TWI peripheral device.

Set command 

The set command allows you to write data to a TWI peripheral device.

Syntax

#XTWIW=<index>,<dev_addr>,<data>

The <index> parameter accepts the following integer values:
- 0 - Use TWI0 (i2c0).
- 1 - Use TWI1 (i2c1).
- 2 - Use TWI2 (i2c2).
- 3 - Use TWI3 (i2c3).
See nordic,nrf-twi.
The <dev_addr> parameter is a hexadecimal string. It represents the peripheral device address to write to. The maximum length is 2 characters (for example, “DE” for 0xDE).
The <data> parameter is a hexadecimal string. It represents the data to be written to the peripheral device. The maximum length is 255 characters (for example, “DEADBEEF” for 0xDEADBEEF).

Response syntax

There is no response.

Example

The following example is meant for Thingy:91.

It performs a write operation to the device address 0x76 (BME680), and it writes D0 to the device.

AT#XTWIW=2,"76","D0"
OK

Read command 

The read command is not supported.

Test command 

The test command is not supported.

Read from TWI peripheral device #XTWIR 

The #XTWIR command reads data from a TWI peripheral device.

Set command 

The set command allows you to read data from a TWI peripheral device.

Syntax

#XTWIR=<index>,<dev_addr>,<num_read>

The <index> parameter accepts the following integer values:
- 0 - Use TWI0 (i2c0).
- 1 - Use TWI1 (i2c1).
- 2 - Use TWI2 (i2c2).
- 3 - Use TWI3 (i2c3).
The <dev_addr> parameter is a hexadecimal string. It represents the peripheral device address to read from. The maximum length is 2 characters (for example, “DE” for 0xDE).
The <num_read> parameter is an unsigned 8-bit integer. It represents the amount of data to read from the peripheral device. The available range is from 0 to 255 bytes.

Response syntax

#XTWIR:
<data>

The <data> parameter is a hexadecimal string. It represents the data read from the peripheral device.

Example

The following example is meant for Thingy:91.

It performs a read operation to the device address 0x76 (BME680), and it reads 1 byte from the device. The value returned (61) indicates 0x61 as the CHIP ID.

AT#XTWIR=2,"76",1

#XTWIR: 61
OK

Read command 

The read command is not supported.

Test command 

The test command is not supported.

Write data and read from TWI peripheral device #XTWIWR 

The #XTWIWR command writes data to a TWI peripheral device and then reads data from the device.

Set command 

The set command allows you to first write data to a TWI peripheral device and then read the returned data.

Syntax

#XTWIW=<index>,<dev_addr>,<data>,<num_read>

The <index> parameter accepts the following integer values:
- 0 - Use TWI0 (i2c0).
- 1 - Use TWI1 (i2c1).
- 2 - Use TWI2 (i2c2).
- 3 - Use TWI3 (i2c3).
See nordic,nrf-twi.
The <dev_addr> parameter is a hexadecimal string. It represents the peripheral device address to write to. The maximum length is 2 characters (for example, “DE” for 0xDE).
The <data> parameter is a hexadecimal string. It represents the data to be written to the peripheral device. The maximum length is 255 characters (for example, “DEADBEEF” for 0xDEADBEEF).
The <num_read> parameter is an unsigned 8-bit integer. It represents the amount of data to read from the peripheral device. The available range is from 0 to 255 bytes.

Response syntax

#XTWIWR:
<data>

The <data> parameter is a hexadecimal string. It represents the data read from the peripheral device.

Examples

The following example is meant for Thingy:91.

It performs a write-then-read operation to the device address 0x76 (BME680) to get the CHIP ID of the device. The value returned (61) indicates 0x61 as the CHIP ID.
```
AT#XTWIWR=2,"76","D0",1

#XTWIWR: 61
OK
```
The following example is meant for Thingy:91.

It performs a write-then-read operation to the device address 0x38 (BH1749) to get the MANUFACTURER ID of the device. The value returned (E0) indicates 0xE0 as the MANUFACTURER ID of the device.
```
AT#XTWIWR=2,"38","92",1

#XTWIWR: E0
OK
```

Read command 

The read command is not supported.

Test command 

The test command is not supported.