MSP432 I2C Master send a NO ACK

Michael Liesenberg85

Mastermind 7560 points

Other Parts Discussed in Thread: TMP423

Hi,

how can the MSP432 send a NO ACK to the slave even if the received bytes are understood?

I am trying to read an EEPROM like this:

Here is my code:

MAP_I2C_masterSendMultiByteStart(EUSCI_B3_BASE, pointer>>8);
MAP_I2C_masterSendMultiByteNext(EUSCI_B3_BASE,(unsigned char)(pointer & 0x00FF));

EUSCI_B_I2C_setMode(EUSCI_B3_BASE, EUSCI_B_I2C_RECEIVE_MODE);
*Data = I2C_masterReceiveSingle(EUSCI_B3_BASE);

But the problem is when it does "masterReceiveSingle" it acknowledges the byte and the EEPROM continues sending data:

So it is doing this:

How do i send a "NO ACK" to the slave and not a ACK using driverlib?

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 278840 points

I2C_masterReceiveSingle() is intended to be used in an interrupt handler (or in the equivalent polling code). To receive the last byte in a transaction and send NACK+STOP afterwards, use I2C_masterReceiveSingleByte().

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

Hi Clemens,

what is the command for a NACK+STOP using driverlib?

0 Clemens Ladisch over 8 years ago in reply to Michael Liesenberg85

Guru 278840 points

See the second sentence of my answer.

The only function to send NACK+STOP without receiving a byte is I2C_masterReceiveMultiByteStop(), but it is to be used only together with the other *MultiByte* functions, and must be called at the correct point in the sequence.

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

ok so if i use I2C_masterReceiveSingleByte() how can i send a NACK after the transaction and not a ACK?
My problem is that the received byte is been ACK as it should be but the EEPROM whants a "NO ACK" at the end.
Is there a way to force a NACK on driverlib?

0 Clemens Ladisch over 8 years ago in reply to Michael Liesenberg85

Guru 278840 points

I2C_masterReceiveSingleByte() automatically sends NACK and STOP.

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

Yes i know but i have to send a NACK at the end even if acknowledges.

How do i force a NACK?

0 Clemens Ladisch over 8 years ago in reply to Michael Liesenberg85

Guru 278840 points

There seems to be a misunderstanding.

What exactly do you think it is that I2C_masterReceiveSingleByte() does wrong?

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

I2C_masterReceiveSingleByte() does the job but at the end when it is doing ACK to the slave it should do a NACK.

Even if the Master understood it it should in this case do a NACK and afterwards a STOP.

The function does a ACK or a NACK automatically but i have to force it to a NACK so that the slave terminates the data transfer and goes to standby mode.

The bus master muss not acknowledge at the 9th time clock so that can happen.

Is there a way of doing that? My slave is the M24128 EEPROM and on the datasheet page 19 it describes the read operations.

0 Clemens Ladisch over 8 years ago in reply to Michael Liesenberg85

Guru 278840 points

Why do you think that I2C_masterReceiveSingleByte() does an ACK?

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

The master does an ACK when it gets and understands the slave transmitted values.
How can i disable it?

0 Clemens Ladisch over 8 years ago in reply to Michael Liesenberg85

Guru 278840 points

With the TXSTP bit. Which is set by, for example, I2C_masterReceiveSingleByte().

0 Michael Liesenberg85 over 8 years ago in reply to Clemens Ladisch

Mastermind 7560 points

Hi Clemens,

the Master Receive I2C protokoll sets a NACK at the end. Driverlib does it as well so i was wrong about it.

Thanks,

Michael

0 Pedro Valladares over 8 years ago in reply to Michael Liesenberg85

Prodigy 60 points

I have a similar issue talking to a TMP423A. It requires a NAK at the end of the read , but I am seeing an ACK and a STOP when using MAP_I2C_masterReceiveSingleByte and not a NAK. I can get the data from the TMP423 once, but the second time the calls timeout. Anyone has figured out how to do this?

Thanks

Pedro

0 Evan Wakefield over 7 years ago in reply to Pedro Valladares

TI__Mastermind 38950 points

Pedro,

Can you provide a code snippet and any scope/logic analyzer shots that you might have?

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MSP432 I2C Master send a NO ACK