MSP430FR5739 UCRXIFG not being set on some bytes

Try with (simple) TI UART examples from slac300 "MSP430F552x C Examples (IAR and CCSv4)".

For LF BR mode (UCOS16 = 0), you can use my calculator (http://forum.43oh.com/topic/2640-uart-configurator) for UART setup.

1 MHz BRCLK is more than enough for 115200 bps, and MSP430 can go over 1 Mbps without problems (http://forum.43oh.com/topic/3413-msp430-uart-benchmark).

I've tried a few different things, all without success. It still only recognizes some characters and not others.

All that is in my main loop (no interrupts) is:

if (UCA0IFG & UCRXIFG)

{

RX_BYTE=UCA0RXBUF;

UCA0IFG &= ~UCRXIFG;

P2OUT ^= BIT6;

} 

and I monitor P2.6 for a toggle.

I tried setting UCOS16 = 0, and just have UCABR0 = 156. same behaviour.

I enabled the SMCLK output and it measured 1.48453MHz, which is only about 1% error.

I tried changing the settings to match that frequency. Same behaviour.

Using a function generator, I put 1.5000MHz into XT1 and ran SMCLK from that source. Same behaviour.

I tried putting in a clock of 1.2288MHz ( 9600*128 = 1228800) and UCA0BR0 = 128 (with UCOS16=0) Same behaviour.

Same1.2288MHz clock with UCA0BR0 = 8, and UCOS16=1. Same behaviour.

 Issue is with the MSP-EXP430FR5739 (Rev1.1) experimenters board. It only supports 9600baud (which is acceptable at this point), but also doesn't have parity support (not ok). Once I removed the UCPEN bit from the setup, it worked. I had expected to get the RX flag first and then read the errors to see I had a parity error (but this isn't how it worked). On parity error the RX flag wasn't thrown nor was the parity error flag thrown.

That would have been nice to have in the documentation for the experimenters board...

 

Jason Rinckey said:

On parity error the RX flag wasn't thrown nor was the parity error flag thrown.

It's possible that you got a framing error instead (when the MSP was receiving the start bit of the next byte as stop bit due to the missing parity bit). Sicne parity is calculated after the stop bit was received, framing error gets diagnosed first and the byte is discarded.

Hi Jason,

Sorry if I'm just stating the obvious, but you must make sure all of the communications settings, not just baud rate, match between the MSP430 and the PC.  Besides baud rate, but there are two other critical settings -- parity (E/O/N) and number of stop bits (1/2).  If you don't configure these settings to match between the MSP430 and the PC, your communication won't work right.

I think the eval kit probably does support parity correctly, but it sounds like you may not have configured the PC to match.

Jeff

Jeff,

That is the first thing that I check. Both had odd parity set, both had 1 stop bit, both had 9600 baud. When I probed the RXD pin, the parity bit was being stripped and a constant value was inserted. For ?? reason the eval board routes the UART data through another microcontroller first, rather than from the USB-UART chip direct to the FR5739. Thus I am stuck at 9600 baud and no parity for this eval board as that is what the other microcontroller is programmed to do. Schematic is in slau272b.