The number of clocks I2C Read.

[Anonymous]

When SCB is used by I2C and it is work at Msster in Creator 4.0, SCB_I2CMastrSendStart() send 17 clocks with read sequence. Although this should be 9 clocks, why does this read send 17 clocks?

By the way, when SCB_I2CMastrSendStart() is used by Write, the write send 9 clocks correctly.

This is worked in PSoC4200 BLE.

[Bob_Marlowe]

Did you configure the I2C component for byte mode?

Bob

[Anonymous]

Hi Bob,

No, I do not use "Byte mode".

I checked API behavior for SCB_I2CMastrSendStart() and SCB_I2CMasterReadByte().

When I use SCB_I2CMastrSendStart() at Read sequence, this API generate Slave address and clocks for read data.

And when I use SCB_I2CMasterReadByte(SCB_I2C_NAK_DATA) for generating Negative Acknowledge, the API does not generate any clocks and return the read data. Whereas using  SCB_I2CMasterReadByte(SCB_I2C_ACK_DATA) for Acknowledge, the API generate clocks to read Slave data and return the read data by having read by former clocks of SCB_I2CMastrSendStart().

But the behavior is different form SCB datasheet.

Best regards,

[ShanmathiN_06 · Accepted solution]

Hi,

The following is the expected behavior of SCB I2C Master in PSoCs:

Write mode-

SCB_I2CMasterSendStart() sends out 8 clocks (Slave address + write bit) + 1 clock (For acknowledge from slave)

SCB_I2CMasterWriteByte() sends out 8 clocks (Byte to be written to slave) + 1 clock (For acknowledge from slave)

When the write operation is completed, send stop condition from master

Read mode-

SCB_I2CMasterSendStart() sends out 8 clocks (Slave address + read bit) + 1 clock (For acknowledge from slave) + 8 clocks (to read the first byte from slave)

SCB_I2CMasterReadByte (SCB_I2C_ACK_DATA) sends out 8 clocks (to read the next byte from slave) + 1 clock (Master ACKs the current byte)

SCB_I2CMasterReadByte (SCB_I2C_NAK_DATA) sends out 1 clock (Master NACKs the current byte), to stop the read transfer; followed by a stop condition sent out from master

Regards,
Shanmathi