Hi! I'm not very experienced with electronics and this is my first try on SPI communication. As title says, I have a PIC connected to my UNO. The idea is to send numbers from the PIC to the UNO via SPI and from there on to my PC via Serial.print . The PIC is powered from the UNO.
For info on how to make the SPI comm work, I have used google and somewhat followed a tutorial from youtube: - YouTube (lessons 18-1 and 18-2)
The codes I made might be totally wrong, I have no idea. Non of my relatives or friends know anything about electronics, so forums are my best hope now.
code on PIC (master):
unsigned char i = 0;
void init(void)
{
ADCON0 = 0;
ADCON1 = 0b0000111;
TRISC.B3 = 0; // SCK
TRISA.B5 = 0; // _SS
TRISC.B5 = 0; // SDO
PORTA.B5 = 1;
PORTC.B3 = 0;
SPI1_Init();
}
void main() {
init();
while(1)
{
for(i=48; i<58; i++)
{
PORTA.B5 = 0;
Delay_ms(100);
SPI1_Write(i);
PORTA.B5 = 1;
Delay_ms(100);
}
}
}
code on UNO (slave):
#include <SPI.h>
int data = 0;
void setup() {
Serial.begin(9600);
pinMode (SS, INPUT);
pinMode (SCK, INPUT);
pinMode (MOSI, INPUT);
pinMode (MISO, OUTPUT);
digitalWrite(SS, HIGH);
digitalWrite(SCK, LOW);
digitalWrite(MOSI, LOW);
digitalWrite(MISO, LOW);
}
void loop() {
Serial.print("SS is HIGH \n");
if (digitalRead(SS) == LOW)
{
Serial.print("SS is LOW \n");
data = SPI.transfer(0x00);
Serial.print(data);
delay(100);
}
delay(10);
}
The problem so far is that UNO's SS pin doesn't ever go LOW and even the string "SS is LOW \n" isn't printed on the monitor although the PIC (master) should constantly pull the SS low with the line PORTA.B5 = 0; .
PIC datasheet: Microchip 0s8qqufexweiah8up1ssdfju22py datasheet pdf
connections: PIC <-> UNO
Vdd <-> 5v
Vss <-> GND
SS <-> pin 10 (SS)
SDO <-> pin 11 (MOSI)
SDI <-> pin 12 (MISO)
SCK <-> pin 13 (SCK)