[PIC] USART connection between two PIC18F Starter Kits

[Victor Badoiu]

Hello,

I am new to PIC18 world and I have a big problem. I bought two PIC18F Stater Kits with PIC18F46J50 microcontroller, Oled display and card reader and I want to connect them using RS232. I already connect the two boards by soldering two wires on D2 and D3 pins.

I've read that I need to use USART2, since USART1 is already connected to the card reader. So, I need to reprogram the pins RD2 and RD3 (RP20 and RP19). The problem is that I cannot find a single demo USART2 that is working. I want to send a string of characters from Board no1. to Board no2. using RS232, and eventually print the characters on the OLED.

Here is a piece of code that I use to transmit the characters. I think it works, but i need another code for board no2, to see something (the receive part).

#define _XTAL_FREQ 8000000 //The speed of your internal(or)external oscillator
 #include <p18cxxx.h>
 #include <usart.h>
 #include <PPS.h>

int i = 0;

 // CONFIG1L
#pragma config WDTEN = OFF          // Watchdog Timer (Disabled - Controlled by SWDTEN bit)
#pragma config PLLDIV =3            // PLL Prescaler Selection bits - Divide by 3 (12 MHz oscillator input)
#pragma config STVREN = ON          // Stack Overflow/Underflow Reset  (Enabled)
#pragma config XINST = OFF          // Extended instruction set disabled

// CONFIG1H
#pragma config CPUDIV = OSC1        // CPU System Clock Postscaler (No CPU system clock divide)
#pragma config CP0 = OFF            // Code Protect (Program memory is not code-protected)

// CONFIG2L
#pragma config OSC = HSPLL          //HS oscillator, PLL enabled, HSPLL used by USB
#pragma config T1DIG = ON           // T1OSCEN Enforcement (Secondary Oscillator clock source may be selected)
#pragma config LPT1OSC = OFF        // Low-Power Timer1 Oscillator (High-power operation)
#pragma config FCMEN = OFF          //Fail-Safe Clock Monitor disabled
#pragma config IESO = OFF           //Two-Speed Start-up disabled

// CONFIG2H
#pragma config WDTPS = 32768        // Watchdog Postscaler (1:32768)

// CONFIG3L
#pragma config DSWDTOSC = INTOSCREF // DSWDT Clock Select (DSWDT uses INTRC)
#pragma config RTCOSC = T1OSCREF    // RTCC Clock Select (RTCC uses T1OSC/T1CKI)
#pragma config DSBOREN = OFF        // Zero-Power BOR disabled in Deep Sleep
#pragma config DSWDTEN = OFF        // Deep Sleep Watchdog Timer (Disabled)
#pragma config DSWDTPS = 8192       //1:8,192 (8.5 seconds)

// CONFIG3H
#pragma config IOL1WAY =OFF         //IOLOCK bit can be set and cleared
#pragma config MSSP7B_EN = MSK7     // MSSP address masking (7 Bit address masking mode)

// CONFIG4L
#pragma config WPFP = PAGE_1        // Write/Erase Protect Page Start/End Location (Write Protect Program Flash Page 0)
#pragma config WPEND = PAGE_0       //Start protection at page 0
#pragma config WPCFG = OFF          //Write/Erase last page protect Disabled

// CONFIG4H
#pragma config WPDIS = OFF             //WPFP[5:0], WPEND, and WPCFG bits ignored

 #define USE_AND_MASKS

unsigned char Txdata[] = "MICROCHIP_USART";
void Delay1Second(void);

 void main (void)
 {
     unsigned char config=0,spbrg=0,baudconfig=0,i=0;

// //------PPS Configuration to map ESUART2 to correct pins ----
// another reconfiguration of the pins
//     PPSUnLock();
//
//     // Configure RD3/RP20 as UART_TX
//     iPPSOutput(OUT_PIN_PPS_RP20, OUT_FN_PPS_TX2CK2);
//
//      // Configure RD2/RP19 as UART_RX
//     iPPSInput(IN_FN_PPS_RX2DT2, IN_PIN_PPS_RP19);
//
//
//     PPSLock();

     // REMAP ID PORT
   
    PPSCON = 0x00;              // unlock peripheral Pin select register
    RPOR19 = 0x05;              // assign USART2 TX to RP19/RD2
    RPINR16 = 0x14;             // assign USART2 RX to RP20/RD3
    PPSCON = 0x01;              // lock peripheral Pin select register

    TRISDbits.TRISD2 = 0;       // TX2 output
    TRISDbits.TRISD3 = 1;       // RX2 input
 //------USART Setup ----

     Close2USART();  //turn off usart if was previously on

     spbrg = 51;

     Open2USART(USART_TX_INT_OFF &
                USART_RX_INT_OFF &
                USART_ASYNCH_MODE &
                USART_EIGHT_BIT &
                USART_CONT_RX &
                USART_BRGH_HIGH, spbrg);

     baudconfig = BAUD_8_BIT_RATE & BAUD_AUTO_OFF;
     baud2USART (baudconfig);

 while(1){

//------USART Transmission ----
    while(Busy2USART());                         //Check if Usart is busy or not
   puts2USART((char *)Txdata);                //transmit the string
    Delay1Second();
}            
 }

 void Delay1Second()
{
    for(i=0;i<100;i++)
    {
         __delay_ms(10);
    }
}

 

[Kurenai_ryu]

Aaaaalways test your communications with a known host.. like communicating each board with a PC first... (go buy a cheap usb/ttl cable to test )

then, what compiler are you using? It seems XC8 but...

finally... did you read the XC8 Peripheral Library Manual? it seems you need to use the OR operator '|' to join the settings

     Open2USART(USART_TX_INT_OFF |
                USART_RX_INT_OFF |
                USART_ASYNCH_MODE |
                USART_EIGHT_BIT |
                USART_CONT_RX |
                USART_BRGH_HIGH, spbrg);

     baudconfig = BAUD_8_BIT_RATE | BAUD_AUTO_OFF;
     baud2USART (baudconfig);

also avoid trying to lock/unlock the PPS, it comes unlocked and for your test it should be enough... (sadly locking/unlocking isn't as easy as setting it to 1 or 0... please read the datasheet for the correct sequence. for the time being, avoid that stuff)