Send STOP after slave ACK on I2C

Adam Ardron

Other Parts Discussed in Thread: TMS320F28377D

Hi,

I am using the I2C module on TMS320F28377D to transmit to an EEPROM. I am following a app note from the manufacturer to test the device.

The example calls for the master (the processor) to send the address followed by a one byte instructions followed by a STOP before proceeding.

I send the address which is acknowledged, the command which is also acknowledged but I cannot send the STOP command.

If I send an incorrect command which is not acknowledged I can successfully send a STOP.

Do I need to do something else or is the TMS320 expecting some data back? The app note specifically calls for a STOP condition at this point.

Thanks and regards,

Adam

over 10 years ago

0 Adam Ardron over 10 years ago

Intellectual 555 points

Hi,

Maybe I can ask this another way!

What condition would make the peripheral unable to send a STOP after a START had been previously sent?

Thanks,

Adam

0 Fulano de Tal over 10 years ago in reply to Adam Ardron

Expert 2090 points

Assuming you are in master TX mode, make sure I2CCNT has the correct number of bytes. STOP won't be sent until it has successfully sent I2CCNT bytes and received ACKs for each. Also make sure STP bit is set in I2CMDR register.

0 Adam Haun over 10 years ago

TI__Expert 8950 points

If Fulano's suggestion doesn't work, please post your source code so we can see what you're doing.

Thanks,

0 Adam Ardron over 10 years ago in reply to Fulano de Tal

Intellectual 555 points

Fulano,

Thanks. Personally I think the datasheet could be a bit clearer on the significance of this register and how it works with the RM bit. After playing around I think I worked it out.

Adam

0 Fulano de Tal over 10 years ago in reply to Adam Ardron

Expert 2090 points

The data sheet doesn't have details for every register, that would be a huge datasheet. There is an entire document dedicated to explaining the I2C module in 2802x and 2803x devices www.ti.com/.../sprufz9d.pdf

0 Adam Ardron over 10 years ago in reply to Fulano de Tal

Intellectual 555 points

Hi Fulano,

Here's one big datasheet. Suppose it's the technical reference manual really!

www.ti.com/.../spruhm8c.pdf

I thought it may be a better bet to have a small section explaining STT, STP, RM and maybe I2CCNT. I2CCNT is only mentioned as a register and nowhere in the preceding text.

Adam

0 Adam Haun over 10 years ago in reply to Adam Ardron

TI__Expert 8950 points

Adam,

I'll try to clarify the documentation when I get a chance. Thanks for the feedback.

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Send STOP after slave ACK on I2C