> For the complete documentation index, see [llms.txt](https://inacks.gitbook.io/inacks-is3720-i2c-dmx+rdm-receiver-ic/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://inacks.gitbook.io/inacks-is3720-i2c-dmx+rdm-receiver-ic/datasheet/i2c-description/single-byte-write.md).

# Single Byte Write

> This page is not the authoritative source for design information. The official [IS3720 datasheet](https://www.inacks.com/is3720) published on [www.inacks.com](http://www.inacks.com) is the authoritative reference: always consult it for the latest information.

Writing a single byte is an action performed by your microcontroller (I2C-master) to write data to any register within the IS3720 memory map (I2C-slave), regardless of the last read or written position. To perform this action, the microcontroller must load the register address intended to be written into the IS3720’s pointer register. Once the address is set, your microcontroller can send the data to be written.

To initiate the single byte write operation, the following steps must be performed from the beginning: your microcontroller begins by pulling down the SDA line while the SCL line is high, creating a Start Condition. It then sends the IS3720 I2C device address 22 with the R/W bit set to 0 (indicating a write operation).

Upon receiving the device address, the IS3720 acknowledges it. Subsequently, your microcontroller sends the two bytes of the register address it intends to write: the most significant byte first, followed by the least significant byte, each acknowledged by the IS3720.

Your microcontroller then sends the byte to be written, which the IS3720 acknowledges. Finally, your microcontroller issues a Stop Condition by raising the SDA line while the SCL line is high.

Invalid Memory Addressing

The valid memory range of the IS3720 for a write operation goes from addresses 0 to 631. If a Write Operation is performed with a Pointer Register higher than 631, the IS3720 will answer with a NACK.

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