Hello,
for my latest project I have developed a board that incorperates a TLC5940 chip and a MCP3208, both use the SPI bus. I can get both chips to work perfectly separate but together they won’t. Do I have to treat the TLC and MCP as independent slaves or can they be daisy chained? The setup I have now is independent so the MOSI and SCK lines are shared (TLC doesn’t use MISO). I use an Arduino Mega 2560. The code I use to test is:
#include "Tlc5940.h"
#define SELPIN 53 //Selection Pin
#define DATAOUT 51//MOSI
#define DATAIN 50//MISO
#define SPICLOCK 52//Clock
int readvalue;
void setup()
{
Wire.begin();
Serial.begin(115200);
Tlc.init();
//set pin modes
pinMode(SELPIN, OUTPUT);
pinMode(DATAOUT, OUTPUT);
pinMode(DATAIN, INPUT);
pinMode(SPICLOCK, OUTPUT);
//disable device to start with
digitalWrite(SELPIN,HIGH);
digitalWrite(DATAOUT,LOW);
digitalWrite(SPICLOCK,LOW);
}
int read_adc(int channel){
int adcvalue = 0;
byte commandbits = B11000000; //command bits - start, mode, chn (3), dont care (3)
//allow channel selection
commandbits|=((channel-1)<<3);
digitalWrite(SELPIN,LOW); //Select adc
// setup bits to be written
for (int i=7; i>=3; i--){
digitalWrite(DATAOUT,commandbits&1<<i);
//cycle clock
digitalWrite(SPICLOCK,HIGH);
digitalWrite(SPICLOCK,LOW);
}
digitalWrite(SPICLOCK,HIGH); //ignores 2 null bits
digitalWrite(SPICLOCK,LOW);
digitalWrite(SPICLOCK,HIGH);
digitalWrite(SPICLOCK,LOW);
//read bits from adc
for (int i=11; i>=0; i--){
adcvalue+=digitalRead(DATAIN)<<i;
//cycle clock
digitalWrite(SPICLOCK,HIGH);
digitalWrite(SPICLOCK,LOW);
}
digitalWrite(SELPIN, HIGH); //turn off device
return adcvalue;
}
void loop()
{
Tlc.set(0,0);
Tlc.update();
readvalue = read_adc(1);
Serial.println(readvalue,DEC);
Serial.println(" ");
delay(2000);
Tlc.set(0,4095);
Tlc.update();
readvalue = read_adc(1);
Serial.println(readvalue,DEC);
Serial.println(" ");
delay(2000);
}
Regards Edwin
