RTS and CTS testing in TL16C754CIPM

1258021

Hi All,

I am using TL16C754CIPM 4-Channel UART Controller.

Among the 4-Channels with first two channels we are using 5-Pin Mode (i.e. Tx, Rx, RTS, CTS and GND).

Now, I wanted to test RTS and CTS functionality on them. So, I want to see a Modem Status Interrupt and /CTS & /RTS change of interrupt.

The corresponding IIR values are IIR = 0x8 and IIR = 0x20.

Fot this I have interconnected Two UART Channels. (CHA.TX to CHB.RX, CHA.RX to CHB.TX, CHA.RTS to CHB.CTS and CHA.CTS to CHB.RTS)

I am changing level of RTS on channel A by writing to MCR[1]. Correspondingly I can see that 0x20 from IIR when ever RTS goes from active to inactive on CHannel A.

But on channel B I see always a Zero value for IIR. But. MSR tpggles between 0xE1 and 0xF1.

The method that I am following is correct?

Please help me in understanding RTS and CTS independently.

Regards,

GSR

over 13 years ago

0 Joe Fockler over 13 years ago

TI__Expert 5230 points

Hi GSR,

What is the setting of the MCR for each channel?

What settings are you using for the EFR[7:6] (Enhanced Features Register) for each channel?

What settings are you using for the IER for each channel?

Are you reading the MSR one time? /CTS status is cleared on a read.

Best Regards,

Joe

0 1258021 over 13 years ago in reply to Joe Fockler

Genius 5120 points

Hi Joe,

Thank You for the reply.

MCR_CHA=0x0c MCR_CHB=0x08

IER_CHA=0xc1 IER_CHB=0xc8

EFR_CHA=0x10 EFR_CHB=0x00

I understand that /CTS status is cleared when we read MSR. Why am I reading MSR is, I guess we should read it after Modem Status Interrupt. Since I am not seeing a modem interrupt I was reading MSR to see if there is any change in that register.

Regards,

GSR

0 1258021 over 13 years ago in reply to 1258021

Genius 5120 points

Hi Joe,

Please let me know if you need any other inputs from me.

Regards,

GSR

0 Joe Fockler over 13 years ago in reply to 1258021

TI__Expert 5230 points

Hi GSR,

Thank you for the register information.

Can you put a scope probe on /CTSB and see if it goes active when you write a '1' to MCR[1] on Channel A?

With MSR toggling between 0xE1 and 0xF1 it seems like the /CTSB signal is behaving correctly. Can you read Channel B's IIR before reading the IIR on Channel A?

Best Regards,

Joe

0 1258021 over 13 years ago in reply to Joe Fockler

Genius 5120 points

When I write a 1 to MCR[1] /CTSB goes low and MSR shows 0xF1.

Similarly when I write a zero MSR shows 0xE1 and /CTSB goes high.

Regards,

GSR

0 1258021 over 13 years ago in reply to 1258021

Genius 5120 points

Hi Joe,

If any other information required I can post it here. Please let me know.

Regards,

GSR

0 Joe Fockler over 13 years ago in reply to 1258021

TI__Expert 5230 points

GSR,

It appears that the signal is behaving correctly but the status is not being updated in the IIR on Channel B.

When configuring the channels try writing a value of 0xC0 to the EFR for Channel A and Channel B.

Best Regards,

Joe

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RTS and CTS testing in TL16C754CIPM