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MAX7219 Display Driver using hardware SPI

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Bill Legge

Joined: 07 Sep 2010
Posts: 24
Location: West Australia

MAX7219 Display Driver using hardware SPI

Posted: Wed Sep 22, 2010 10:34 pm

Code tested on PIC18F8722 with 10MHz xtal. Runs OK at 10MHz(HS) and at 40MHz(PLL or H4).
The 'BAUD=10000' in the '#use spi' can also be left out.

Code:

/////////////////////////////////////////////////////////////////////////////
// Project: 8722 SPI_02\main.c //
// Author: WVL //
// Date: September 2010 //
// Outline: Basic hardware SPI to drive ETT display with decode on: //
// BIGPIC5 board //
// Heartbeat portH.0 //
// 10Mhz Xtal run at 10Mhz using HS //
// 40MHz OK but slower used for good scope display
// Using hwr SPI driving MAX7219 //
/////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////
// Pin assignments BIGPIC5 board //
// PIN FUNCTION //
// C1 MAX load //
// C3 SPI clock //
// C4 SPI data in //
// C5 SPI data out //
// Pin assignments ETT 8 digit display //
// C0 SPI data in //
// C1 Max load //
// C2 SPI clock //
/////////////////////////////////////////////////////////////////////////////

#define DATA PIN_C5 // SPI1 hardware SPI data out
#define LOAD PIN_C1 // software SPI
#define CLK PIN_C3 // SPI1 hardware clock

#include <main.h>
#define LED PIN_H0
// MAX7219 needs: MSB first(default),data on rising clock edge
// Works at maximum rate OK, BAUD rate set for good scope display
#use spi(FORCE_HW,BAUD=10000,SAMPLE_RISE,BITS=8,)

// function to write two bytes to the display
// address_1=RH digit, address_8=LH digit
// decode is on so dis_data=3 displays '3'
void display(char address,char dis_data)
{
output_low(LOAD);
spi_write(address); // spi1 write to default pins
delay_us(10); // used for scope display but not necessary
spi_write(dis_data); // spi1 write to default pins
output_high(LOAD);
}

void main()
{
unsigned int8 x;
unsigned int8 y;

setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2|ADC_TAD_MUL_0);
setup_spi2(SPI_SS_DISABLED);
setup_wdt(WDT_OFF);
setup_timer_0(RTCC_OFF); // PIC18 only
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_timer_4(T4_DISABLED,0,1);
setup_ccp1(CCP_OFF);
setup_comparator(NC_NC_NC_NC);

display(0x0f,0x00); // test mode off
display(0x0B,0x07); // scan limit - 8 columns
display(0x0C,0x01); // Shutdown - normal mode
display(0x09,0xFF); // decode mode on
display(0x0A,0x07); // intensity
for(x=1;x<=8;x++)display(x,0x0f); // blank all digits

while(true)
{
for(x=1;x<=8;x++) // write 1 to 8 on digits 1 to 8
{
display(x,x);
delay_ms(500);
output_toggle(LED);
}// for loop
for (y=0;y<=9;y++) // write 0 to 9 on all digits
{
for (x=1;x<=8;x++)
{
display(x,y);
}// for x loop
delay_ms(500);
}// for y loop
delay_ms(500);
for(x=1;x<=8;x++)display(x,0x0f);
}// while loop
}// main loop

Anyone spots anything daft - please let me know?
_________________
Denmark in West Australia
'Where the forest meets the sea'

Bill Legge

Joined: 07 Sep 2010
Posts: 24
Location: West Australia

MAX7219 Display Driver using hardware SPI

Posted: Fri Sep 24, 2010 5:36 pm

Code works OK but 'PCM programmer' has just kindly pointed out that the line that I thought turned 'SPI2' off did not do so - I've corrected the line in this listing:

Code:

/////////////////////////////////////////////////////////////////////////////
// Project: 8722 SPI_02\main.c //
// Author: WVL //
// Date: September 2010 //
// Outline: Basic hardware SPI to drive ETT display with decode on: //
// BIGPIC5 board //
// Heartbeat portH.0 //
// 10Mhz Xtal run at 10Mhz using HS //
// 40MHz OK but slower used for good scope display
// Using hwr SPI driving MAX7219 //
/////////////////////////////////////////////////////////////////////////////

/////////////////////////////////////////////////////////////////////////////
// Pin assignments BIGPIC5 board //
// PIN FUNCTION //
// C1 MAX load //
// C3 SPI clock //
// C4 SPI data in //
// C5 SPI data out //
// Pin assignments ETT 8 digit display //
// C0 SPI data in //
// C1 Max load //
// C2 SPI clock //
/////////////////////////////////////////////////////////////////////////////

#define DATA PIN_C5 // SPI1 hardware SPI data out
#define LOAD PIN_C1 // software SPI
#define CLK PIN_C3 // SPI1 hardware clock

#include <main.h>
#define LED PIN_H0
// MAX7219 needs: MSB first(default),data on rising clock edge
// Works at maximum rate OK, BAUD rate set for good scope display
#use spi(FORCE_HW,BAUD=10000,SAMPLE_RISE,BITS=8,)

// function to write two bytes to the display
// address_1=RH digit, address_8=LH digit
// decode is on so dis_data=3 displays '3'
void display(char address,char dis_data)
{
output_low(LOAD);
spi_write(address); // spi1 write to default pins
delay_us(10); // used for scope display but not necessary
spi_write(dis_data); // spi1 write to default pins
output_high(LOAD);
}

void main()
{
unsigned int8 x;
unsigned int8 y;

setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2|ADC_TAD_MUL_0);
setup_spi2(FALSE); // this is the corrected line ************
setup_wdt(WDT_OFF);
setup_timer_0(RTCC_OFF); // PIC18 only
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_timer_4(T4_DISABLED,0,1);
setup_ccp1(CCP_OFF);
setup_comparator(NC_NC_NC_NC);

display(0x0f,0x00); // test mode off
display(0x0B,0x07); // scan limit - 8 columns
display(0x0C,0x01); // Shutdown - normal mode
display(0x09,0xFF); // decode mode on
display(0x0A,0x07); // intensity
for(x=1;x<=8;x++)display(x,0x0f); // blank all digits

while(true)
{
for(x=1;x<=8;x++) // write 1 to 8 on digits 1 to 8
{
display(x,x);
delay_ms(500);
output_toggle(LED);
}// for loop
for (y=0;y<=9;y++) // write 0 to 9 on all digits
{
for (x=1;x<=8;x++)
{
display(x,y);
}// for x loop
delay_ms(500);
}// for y loop
delay_ms(500);
for(x=1;x<=8;x++)display(x,0x0f);
}// while loop
}// main loop

Regards Bill Legge
_________________
Denmark in West Australia
'Where the forest meets the sea'

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