UART questions

[prstein]

Hello Christopher,

I'd be very interested to know which UART chip you are using.

A different approach could be to utilize the UART for the serial communications and use the software SPI commands (SHIFTIN and SHIFTOUT). I would be lost without the PIC's two-byte buffer and interrupt...8v)

Best Regards,
Paul

[Christopher4187]

It's the RN-171. I'm using this code and I can see the data coming out of the RN-171 and into the 4550 but the 4550 isn't doing anything. Am I at least in the ballpark?

DEFINE OSC 48

@ __CONFIG _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@ __CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
@ __CONFIG _CONFIG2L, _PWRT_OFF_2L & _BOR_OFF_2L & _BORV_3_2L & _VREGEN_ON_2L
@ __CONFIG _CONFIG2H, _WDT_OFF_2H & _WDTPS_32768_2H 
@ __CONFIG _CONFIG3H, _CCP2MX_ON_3H & _PBADEN_OFF_3H & _LPT1OSC_OFF_3H & _MCLRE_ON_3H
@ __CONFIG _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _ICPRT_ON_4L & _XINST_OFF_4L

 CMCON = 7 
 PORTD.1=0 'diagnostic LED
 PORTD.0=0 'diagnostic LED


DEFINE HSER_BAUD 9600
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_CLROERR 1

in1 var byte

HIGH PORTD.0
HIGH PORTD.1


mainloop:

IF RCSTA.1 = 1 THEN    'if USART overrun error flag OERR is set...
   RCSTA.4 = 0          'clear and then set CREN bit to recover
   RCSTA.4 = 1
   in1 = RCREG          'read data to clear out RCREG
   IF PIR1.5 = 1 THEN in1 = RCREG   'clear possible 2nd byte in RCREG
ENDIF


WHILE PIR1.5 = 0   'stay here until USART receives data

  
WEND
LOW portD.0       'data in RCREG; turn on diagnostic LED   <----my code won't go past this point even though I can see data being sent with an oscope.

goto mainloop

[Christopher4187]

Nevermind. Apparently I either need glasses or sleep.

[prstein]

Hello Christopher,

I see a couple of things. To make the USART work on the '4550 the manual says that both the RX and TX pins need to be configured as inputs, so add

TRISC.7 = 1
TRISC.6 = 1

If you're having trouble, try remming out the first six lines under mainloop, from the if to the endif, just to confirm that the port is working asynchronously.

For synchronous operations, TRISC.7 needs to be set to 0.

Best Regards,
Paul

[Christopher4187]

I have everything working for the most part. It's a little buggy but hopefully I can sort that out over time. I have a question about sorting the data. The data comes to me in this form:

*DATA* 84 324 2343 211 2345 234 DONE
ID: 24

I want to take the six numbers on the first line and assign variables to them and then do stuff with them. How can I do that? Also, if I was to push out 100 variables in one shot, would that work or is it considered normal practice?

[Christopher4187]

One other question. When I'm using SPI, my settings are as follows:

SSPSTAT = %01100100      
 SSPCON1 = %00100001 
 BAUDCON = %00001111

When I switch to UART, I do the following:

SELECT case TIMER
        CASE 255
            SSPSTAT = 0     
            SSPCON1 = 0
            BAUDCON = 0
            PAUSE 1000
            for x=1 to 10
            HSEROUT ["FAN: ",DEC FAN]
            pause 10
            next x
            SSPSTAT = %01100100      
            SSPCON1 = %00100001 
            BAUDCON = %00001111
            pause 100
    END SELECT

Using one or the other (initial programming), it works correctly. When I use the code above, the data goes out but it's garbled. Instead of the fan information, I get stuff like "*Œ€’ŽŒ�âì "

Any ideas?