PIC32mx UART scrambled text

clockpicuart

I'm trying to communicate with a PIC32MX795F512H using UART but I get scrambled signs in my terminal.

I know it's a timing/clock issue but I have no idea where and how to fix it.
I am not using an external crystal and nothing is connected to the PIC (except the necessary minimum (caps, wires and a resistor)).

The code:

#include <p32xxxx.h>
#include <plib.h>

#pragma config FPLLMUL = MUL_20, FPLLIDIV = DIV_2, FPLLODIV = DIV_1, FWDTEN = OFF
#pragma config POSCMOD = HS, FNOSC = PRIPLL, FPBDIV = DIV_1

#define DESIRED_BAUDRATE    (9600)
#define SYSCLK          (80000000L)

#define CONFIG1 (ADC_MODULE_ON | ADC_FORMAT_INTG32 | ADC_CLK_AUTO |      ADC_AUTO_SAMPLING_ON)
#define CONFIG2 (ADC_VREF_AVDD_AVSS | ADC_OFFSET_CAL_DISABLE | ADC_SCAN_ON | ADC_SAMPLES_PER_INT_1 | ADC_ALT_BUF_OFF | ADC_ALT_INPUT_OFF)
#define CONFIG3 (ADC_CONV_CLK_INTERNAL_RC | ADC_SAMPLE_TIME_15)
#define CONFIGPORT (ENABLE_AN15_ANA)
#define CONFIGSCAN (SKIP_SCAN_AN0 | SKIP_SCAN_AN1 | SKIP_SCAN_AN2 | SKIP_SCAN_AN3 | SKIP_SCAN_AN4 | SKIP_SCAN_AN5 | SKIP_SCAN_AN6 | SKIP_SCAN_AN7 | SKIP_SCAN_AN8 | SKIP_SCAN_AN9 | SKIP_SCAN_AN10 | SKIP_SCAN_AN11 | SKIP_SCAN_AN12 |  SKIP_SCAN_AN13 |  SKIP_SCAN_AN14)

unsigned char data;
int pbClk;


void initializeADC(){
    CloseADC10();       // Generally, you should disable the ADC before setup.

    SetChanADC10( ADC_CH0_NEG_SAMPLEA_NVREF);
    OpenADC10( CONFIG1, CONFIG2, CONFIG3, CONFIGPORT, CONFIGSCAN);
                // Setup for the ADC10.
    EnableADC10();      // Enables the ADC10.
    while(!mAD1GetIntFlag() ) {}; // mAD1GetIntFlag() checks the interrupt flag for the AD10.
                      // Waits till a conversion is finished so that there's
                      // values in the ADC result registers.
}

void initializeLEDBar(){
    TRISDCLR = 0xFF;    // Sets pins RD0 to RD7 as digital outputs.
}

void initializeUART()
{
    // Optimize PIC32 performance and return peripheral bus frequency
    pbClk=SYSTEMConfig(SYSCLK, SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE);

    // Enable UART1 and set baud rate to DESIRED_BAUDRATE=9600
    OpenUART1(UART_EN, UART_RX_ENABLE | UART_TX_ENABLE, pbClk/16/DESIRED_BAUDRATE-1);

    while(BusyUART1()); // Wait until the UART module is free
    putsUART1("Turning the potentiometer will change characters on screen!");
} 


//     ==============================================================================================

int main(){
    initializeUART();   // Initialize the UART module
    initializeADC();    // Initialize the ADC10
    initializeLEDBar(); // Initialize pins RD0 - RD7 as digital outputs

    while(1){

        // Map the 10 bit analog value to a value between 33 and 126, and bit-mask it to 8-bits
        data = ((ReadADC10(0)/11) + 33) & 0xFF;
        LATD = data;                // Latch the data to the port D pins  

        while(BusyUART1());         // Wait until UART2 module is not busy
        putcUART1(data);            // Transmit 'data' through UART
        putcUART1('13');            // Transmit '13' (carriage return)
    }
    return 1;
}

Best Answer

putcUART1(data);            // Transmit 'data' through UART

The "data" will be put out in binary aka "scrambled signs". On the terminal you'll likely want hex or decimal chars: You need to convert the data first.

putcUART1('13');            // Transmit '13' (carriage return)

The code does not match the comment. BTW: This should generate a compiler warning about a multi-character constant. Correct this to:

putcUART1(13);

This will output a CR.

I recommend reading a book about the C programming language. Then you will understand much better what happened and why.

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