MSP430FR2532: The difference between BULK_I2C and REGISTER_I2C

Hello Keigo,

Yes. For the REGISTER_I2C, the I2C master need to write the command ID before reading from the slave (CapTIvatae) device. 

For example, if we want to read the sensor packet for sensor 0X00.

1. The master (host) requested a sensor packet by writing the first two bytes of the sensor packet it wanted. The first two bytes indicate to the slave device what data to fetch for the host. Sensor packets are fixed length packets (always 6 bytes) that indicate the general status of a sensor. For button sensors, this includes information such as the dominant button that is being touched. For slider and wheel sensors, this includes the calculated slider/wheel position. Review the CapTIvate Protocol Sensor Packet description for details on the packet structure. The basic format is shown below:

The first two bytes (shaded darker) include the CMD byte and the Sensor ID byte. The CMD byte tells the slave to fetch a sensor packet. The command ID for a sensor packet is 0x00. The Sensor ID byte tells the slave which sensor to fetch the packet for. In this case, we asked for Sensor ID 0x00, which corresponds to the button group sensor. These are the two items that are needed for reading a sensor packet.

2.  Following the host requesting the packet, the host performs a read of the data to retrieve the entire packet that was generated by the slave (CapTIvate) device. This means that all 6 bytes of the sensor packet are read out of the device. 

You can find more information about packet types from our CapTIvate Technology Guide Packet Types Section 

Please let me know if you have any questions.

Regards,

Yiding