PIC18F2450 Rs-232

[PlantBob]

I have a Olimex PIC-28 board. I have a PIC18F2450 and a ST232 installed.

I have pin 17 on the PIC18F connected to pin 12 on the ST232
I have pin 18 on the PIC18F connected to pin 10 on the ST232

I am using this command in PBP:
SEROUT PORTC.6,T9600,["This is a test"]

I have a scope attached and the PIC pins 17 and 18 are always high, they never change.

Is my wiring wrong? or do I have to set some configuration bits to make this work?

Thanks,
Bob

[PlantBob]

BTW,
the SEROUT PORTC.6,T9600,["This is a test"] command is in a loop that updates every 2 seconds.

[PlantBob]

More Information:

TRISC = %10111111 ' Set TX (PortC.6) to out, rest in
TRISB = %00000000 ' Set PortB to outputs
TRISA = %01111111
SPBRG = 25 ' Set baud rate to 2400
RCSTA = %10010000 ' Enable serial port and continuous receive
TXSTA = %00100000 ' Enable transmit and asynchronous mode
INTCON2.7 = 0

[SKOLS1]

If you want to control ports.Frist of all change them to "0",with this command PORTB=$00

[PlantBob]

TRISB = %00000000 is the same thing and that is already in my code.
I don't think Portb has anything to do with my USART operations.

[mackrackit]

TRISB = XXX
PORTB = XXX
are not the same thing. One sets direction and the other is on/off.

What happens if you pull the 232 chip?

[ScaleRobotics]

What configs are you using? If it is the default ones in pbp/18f2450.inc then they are set to:

        __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    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
        __CONFIG    _CONFIG3H,_PBADEN_OFF_3H & _LPT1OSC_OFF_3H & _MCLRE_ON_3H
        __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _BBSIZ_BB1K_4L & _XINST_OFF_4L

That should get you 48 mhz instead of 20 mhz.

And for the hardware, do you have the 3.3 volt jumper on, or off?

Can you get the chip to blink an LED or something to make sure its running?

If you decide to go with hardware uart here are some defines for 48 mhz.

'DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
'DEFINE HSER_TXSTA 20h ' Enable transmit, BRGH = 0
'DEFINE HSER_SPBRG 77 ' 9600 Baud @ 48MHz, 0.16%
'DEFINE HSER_CLROERR 1 ' Clear overflow automatically

[PlantBob]

I have an external 20mhz oscillator. Can you tell me what I need to do to use SEOUT2 and SERIN2 on pins PORTB.5 and PORTB.4?

[ScaleRobotics]

I have an external 20mhz oscillator. Can you tell me what I need to do to use SEOUT2 and SERIN2 on pins PORTB.5 and PORTB.4?

Hi Bob,

Are you able to blink an led with the chip? It may sound stupid, but that eliminates a lot of other issues.

With the 20 mhz external OSC and the default configs, your chip will run at 48 mhz. So if you are using the default configs, you will have to define your OSC. You might also try Darrel's All Digital. It takes care of some of the analog settings that can throw us for a loop. It is located here: http://www.picbasic.co.uk/forum/cont...54-All-Digital
Im away from my PBP right now, but you should be able to use the PBP serout example from the manual.

Let us know if you get stuck.

[Bruce]

You definitely do not want to enable the hardware USART if you want to use any bit-banged serial routines like SEROUT/SERIN or SEROUT2/SERIN2 on the hardware RX/TX pins.

Enabling the hardware USART prevents you from using the TX/RX pins as digital, so bit-banged serial commands can't control these pins.

And double-check your connections to the ST232. I suspect you have TX and RX backwards.

[ScaleRobotics]

And double-check your connections to the ST232. I suspect you have TX and RX backwards.

he is using this board http://www.olimex.com/dev/pic-p28.html so wiring should be correct. (for the hardware serial port that is)