MAX7219 LED Driver Help needed...

[wmeade]

I am trying to drive 2 7 segment leds using a 16F877 with a MAX7219 LED Display Driver chip using PICC SPI Drivers. I have done a search of the forum and found 4 references that I have used to accomplish this. I am only getting the decimal points to blink when I turn on the proto-board. My code is below and any help will be greatly appreciated. All I am trying to do in the program is put a number '8' on LED 0.

As you can see in the setup_spi line, I had to use comas and not the | between the Parameters. Why is this? Is that why it is not working?

[Mark]

The setup_spi() is a function call. It should go inside a routine. The way you have it, the compiler thinks that it is a function prototype, thus the error when you compiled with the "|". Yes it should be "|". You should also have an endless loop in your main to prevent the processor from executing a hidden sleep command. I didn't check your code but I made corrections where I know there were problems.

[cxiong]

I have found this post in the forum and I try it, it does not work.
I just does not turn on the LED at all. I use the LDQ-N512RI with
the Max7219. I just need to drive the first 2 digit according to this post.
I modified the code to use my 4Mhz, and pin RC5 to max_din, and max_cs
to pin RC0.

Here is my code:

[Guest]

Here is the latest code I have. I have the code to display 8405 on digit 0-3. It does not display the 8405, it display a.a.a.a. on the LED. and I can't control the intensity of the display by low the the hex under register address: 0x0A.

Here is my code:

[drh]

Read the datasheet for the MAX7219 again.
The code for 50% intensity is 0x07.
The part is in shutdown at powerup. Why are you taking it out of test mode?
Use

[wlasoi@saci.ubu.ac.th]

#include<18f452.h>
#fuses xt,nowdt,put,noprotect
#use delay(clock=4000000)

#define da pin_c0
#define cs pin_c1
#define clk pin_c2

void send_16bit(byte address,byte data)
{
byte i;
#bit carry=0x03.0;
carry=0;
output_low(cs);
for(i=0;i<8;i++)
{
if((address & 0b10000000)==0)
output_low(da);
else
output_high(da);
rotate_left(&address,1);

output_high(clk);
delay_us(50);
output_low(clk);
delay_us(50);
}

for(i=0;i<8;i++)
{
if((data & 0b10000000)==0)
output_low(da);
else
output_high(da);

rotate_left(&data,1);
output_high(clk);
delay_us(50);
output_low(clk);
delay_us(50);
}
output_high(cs);
}

void init_7219()
{
send_16bit(0x09,0xff); //decode
delay_us(100);
send_16bit(0x0a,0x0f); //intensity
delay_us(100);
send_16bit(0x0b,0x07); //scan limit
delay_us(100);
send_16bit(0x0c,0x01); //shutdown
delay_us(100);
send_16bit(0x0f,0x00); //display
delay_us(100);
}


main()
{
int i,j;
set_tris_c(0x00);
init_7219();
delay_ms(1000);

while(1){
for(i=1;i<=8;i++){
for(j=0;j<=9;j++){
send_16bit(i,j);
delay_ms(200);
}
}
}
}

[Guest]

I want to display the result of ADC result into the 7-segments in decimal,
example 0-255.

How do I separate these numbers such as one, tenth, hundredth out from
the ADC result and display them in the 7-segments.

I have been searching for a very simple way (theory) how to do it, I can't
one that simple enough for me to understand.

Any body give me a direction or a simple theory (explanation) how to do that?

Thanks...

[Mark]

Well the simplest way would be to divide by 10. The remainder would be the digit.

[Guest]

Hi Mark

I just want clear

example, the adc result is equal to 123

is the above code which divide by 10 will work?

my calculation is

123 / 10 = 12 remainder 3 (3 is the digit1)

123 / 10 = 12 remainder 3 (so the digit10 is also 3?)

Can you explain little bit?

Thanks..

[treitmey]

He is using the /= so the result is the previous result divided by 10
result=123/10=12 R3
result=12/10 =1 R2
result=1/10 = 0 R1

your interested in the remainder

Its like hacking off a digit at a time. hack off 3 then 2 then 1

[cxiong]

How do I display the ds1307 (hh:mm) into the 7-segment using max7219?

What is the best way to do it? Theory?

[Guest]

Can not display the hour and minutes digits into 7-segment.

My questions are:

1. I can not initialize both of the ds1307 and max7219, I think they are
conflict when I run the init_7219(); and the init_ds1307();
in my main code because both use the RC3, RC4 pins.


2. I can not think of a way to single out the following min into minh
and minl, and single out the hrs into hrh and hrl so I can display
their individual digit into their proper location on the 7-segments.

[Guest]

Can not display the hour and minutes digits into 7-segment.

My questions are:

1. I can not initialize both of the ds1307 and max7219, I think they are
conflict when I run the init_7219(); and the init_ds1307();
in my main code because both use the RC3, RC4 pins.


2. I can not think of a way to single out the following min into minh
and minl, and single out the hrs into hrh and hrl so I can display
their individual digit into their proper location on the 7-segments.

[Guest]

Can not display the hour and minutes digits into 7-segment.

My questions are:

1. I can not initialize both of the ds1307 and max7219, I think they are
conflict when I run the init_7219(); and the init_ds1307();
in my main code because both use the RC3, RC4 pins.


2. I can not think of a way to single out the following min into minh
and minl, and single out the hrs into hrh and hrl so I can display
their individual digit into their proper location on the 7-segments.

[Guest]

I am sorry for the tripple post, every time I click the submit button, it
show an error, I thought it did not successful, so I did click it 3 times and it display the same message 3 times.

Sorry.