Clarification of I2C_DRV_MasterReceiveDataBlocking() parameters

davepfaltzgraff — Mon, 09 Mar 2015 18:23:39 GMT

I'm trying to use the I2C_DRV_MasterXXXDataBlocking parameters and need some clarification. The following is my interpretation and I would like comments for clarification. (My environment is Windows7, KDS, KSDK, PE, and MQX on FRDM-K22F.)

The documentation states (simplified with my annotation):

====

I2C_DRV_MasterReceiveDataBlocking (

instance, // Which I2C Bus

device, // Address on I2C bus (7-bit width)

cmdBuff, // If not NULL, commands to be sent

cmdSize, // If not zero, number of bytes sent as command IF cmdBuff is not NULL

// If command was sent, a restart applied

// and I2C Address sent with a READ cycle

rxBuff, // Memory location for data read

rxSize, // Number of bytes to read , unless terminated by device

timeout_ms );// Time out in milliseconds (API states microseconds!)

====

My question is: If cmdBuff is NULL, does the driver issue a read to the device without sending out the command first? In other words, the restart cycle is never performed.

I have the same question on the I2C_DRV_MasterReadDataBlocking() function as well.

In these cases I would expect to see the I2C bus go immediately into the appropriate transfer. Am I correct in this interpretation?

Thanks

Re: Clarification of I2C_DRV_MasterReceiveDataBlocking() parameters

chris_brown — Mon, 09 Mar 2015 18:59:06 GMT

Hi David,

In the case you mention (passing NULL for cmdBuff and cmdSize), you should NOT see a repeated start. The device would expect to start receiving data from the slave immediately.

Regards,

Chris

topic Clarification of I2C_DRV_MasterReceiveDataBlocking() parameters in Kinetis Software Development Kit

Clarification of I2C_DRV_MasterReceiveDataBlocking() parameters

Re: Clarification of I2C_DRV_MasterReceiveDataBlocking() parameters