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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Max7221 and dot matrix displays |
 Posted: Mon May 28, 2007 7:55 am |
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Hallo,
I have post already several times about this problem
Have 10 5x7 dotmatrix displays connected to ten cascaded MAX7221's
This is my code so far
It displays "TEST" on the rightmost matrix displays
| Code: |
#include <18F4620.h>
#include <stdlib.h>
#use delay(clock=20000000)
#fuses HS,NOWDT,NOBROWNOUT,NOPUT,NOLVP,DEBUG,NOSTVREN,NOPROTECT
#include <max7221_5x7_dot_matrix.h>
void main() {
char input_buffer[11];
max7221_init();
max7221_blank_dot_matrix();
while(TRUE) {
strcpy(input_buffer,"TEXT 1");
max7221_fill_buffer(input_buffer);
max7221_display_message();
delay_ms(1000);
strcpy(input_buffer,"TEXT 2");
max7221_fill_buffer(input_buffer);
max7221_display_message();
delay_ms(1000);
}
}
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| Code: |
#ifndef MAX7221_CS
#define MAX7221_CS PIN_C0
#define MAX7221_CLK PIN_C3
#define MAX7221_DOUT PIN_C4
#define MAX7221_DIN PIN_C5
#endif
// Register address map
#define NO_OP 0x00 // Used when cascading max7221s
#define DIGIT_0 0x01 // Digit 0 register
#define DIGIT_1 0x02 // Digit 1 register
#define DIGIT_2 0x03 // Digit 2 register
#define DIGIT_3 0x04 // Digit 3 register
#define DIGIT_4 0x05 // Digit 4 register
#define DIGIT_5 0x06 // Digit 5 register
#define DIGIT_6 0x07 // Digit 6 register
#define DIGIT_7 0x08 // Digit 7 register
#define DECODE_MODE 0x09 // Decode mode register
#define INTENSITY 0x0A // Intensity register
#define SCAN_LIMIT 0x0B // Scan-limit register
#define SHUT_DOWN 0x0C // Shutdown register
#define DISPLAY_TEST 0x0F // Display-test register
// Shutdown register
#define SHUTDOWN_MODE 0x00 // Shutdown mode
#define NORMAL_MODE 0x01 // Normal mode
// Decode-mode register
#define NO_DECODE_DIGITS_7_0 0x00 // No decode for digits 7-0
#define CODE_B_DECODE_DIGIT_0 0x01 // Code B decode for digit 0
#define CODE_B_DECODE_DIGITS_3_0 0x0F // Code B decode for digits 3-0
#define CODE_B_DECODE_DIGITS_7_0 0xFF // Code B decode for digits 7-0
// Intensity register
#define DUTY_CYCLE_1 0x00 // Intensity min
#define DUTY_CYCLE_2 0x01
#define DUTY_CYCLE_3 0x02
#define DUTY_CYCLE_4 0x03
#define DUTY_CYCLE_5 0x04
#define DUTY_CYCLE_6 0x05
#define DUTY_CYCLE_7 0x06
#define DUTY_CYCLE_8 0x07
#define DUTY_CYCLE_9 0x08
#define DUTY_CYCLE_10 0x09
#define DUTY_CYCLE_11 0x0A
#define DUTY_CYCLE_12 0x0B
#define DUTY_CYCLE_13 0x0C
#define DUTY_CYCLE_14 0x0D
#define DUTY_CYCLE_15 0x0E
#define DUTY_CYCLE_16 0x0F // Intensity full
// Scan-limit register
#define DISPLAY_DIGIT_0 0x00 // Display digit 0
#define DISPLAY_DIGITS_01 0x01 // Display digits 0 & 1
#define DISPLAY_DIGITS_012 0x02 // Display digits 0 1 2
#define DISPLAY_DIGITS_0123 0x03 // Display digits 0 1 2 3
#define DISPLAY_DIGITS_01234 0x04 // Display digits 0 1 2 3 4
#define DISPLAY_DIGITS_012345 0x05 // Display digits 0 1 2 3 4 5
#define DISPLAY_DIGITS_0123456 0x06 // Display digits 0 1 2 3 4 5 6
#define DISPLAY_DIGITS_01234567 0x07 // Display digits 0 1 2 3 4 5 6 7
// Display-test register
#define NORMAL_OPERATION 0x00 // Normal operation
#define DISPLAY_TEST_MODE 0x01 // Display-test mode, all leds on
// Number max. dot-matrix displays
#define MAX_DOT_MATRIX_USED 0x0A // Max. dot matrix displays used
// Declare and Init the font array data
char const font5x7[96][5] = {
0x00, 0x00, 0x00, 0x00, 0x00 // 0x20, Space
0x00, 0x00, 0x5F, 0x00, 0x00 // 0x21, !
0x00, 0x07, 0x00, 0x07, 0x00 // 0x22, "
0x14, 0x7F, 0x14, 0x7F, 0x14 // 0x23, #
0x12, 0x2A, 0x7F, 0x2A, 0x24 // 0x24, $
0x62, 0x64, 0x08, 0x13, 0x23 // 0x25, %
0x50, 0x22, 0x55, 0x49, 0x36 // 0x26, &
0x00, 0x00, 0x03, 0x05, 0x00 // 0x27, '
0x00, 0x41, 0x22, 0x1C, 0x00 // 0x28, (
0x00, 0x1C, 0x22, 0x41, 0x00 // 0x29, )
0x08, 0x2A, 0x1C, 0x2A, 0x08 // 0x2A, *
0x08, 0x08, 0x3E, 0x08, 0x08 // 0x2B, +
0x00, 0x00, 0x30, 0x50, 0x00 // 0x2C, ,
0x08, 0x08, 0x08, 0x08, 0x08 // 0x2D, -
0x00, 0x00, 0x60, 0x60, 0x00 // 0x2E, .
0x02, 0x04, 0x08, 0x10, 0x20 // 0x2F, /
0x3E, 0x45, 0x49, 0x51, 0x3E // 0x30, 0
0x00, 0x40, 0x7F, 0x42, 0x00 // 0x31, 1
0x46, 0x49, 0x51, 0x61, 0x42 // 0x32, 2
0x31, 0x4B, 0x45, 0x41, 0x21 // 0x33, 3
0x10, 0x7F, 0x12, 0x14, 0x18 // 0x34, 4
0x39, 0x45, 0x45, 0x45, 0x27 // 0x35, 5
0x30, 0x49, 0x49, 0x4A, 0x3C // 0x36, 6
0x03, 0x05, 0x09, 0x71, 0x01 // 0x37, 7
0x36, 0x49, 0x49, 0x49, 0x36 // 0x38, 8
0x1E, 0x29, 0x49, 0x49, 0x06 // 0x39, 9
0x00, 0x00, 0x36, 0x36, 0x00 // 0x3A, :
0x00, 0x00, 0x36, 0x56, 0x00 // 0x3B, ;
0x41, 0x22, 0x14, 0x08, 0x00 // 0x3C, <0x14>
0x06, 0x09, 0x51, 0x01, 0x02 // 0x3F, ?
0x3E, 0x41, 0x79, 0x49, 0x32 // 0x40, @
0x7E, 0x11, 0x11, 0x11, 0x7E // 0x41, A
0x36, 0x49, 0x49, 0x49, 0x7F // 0x42, B
0x22, 0x41, 0x41, 0x41, 0x3E // 0x43, C
0x1C, 0x22, 0x41, 0x41, 0x7F // 0x44, D
0x41, 0x49, 0x49, 0x49, 0x7F // 0x45, E
0x01, 0x01, 0x09, 0x09, 0x7F // 0x46, F
0x32, 0x51, 0x41, 0x41, 0x3E // 0x37, G
0x7F, 0x08, 0x08, 0x08, 0x7F // 0x48, H
0x00, 0x41, 0x7F, 0x41, 0x00 // 0x49, I
0x01, 0x3F, 0x41, 0x40, 0x20 // 0x4A, J
0x41, 0x22, 0x14, 0x08, 0x7F // 0x4B, K
0x40, 0x40, 0x40, 0x40, 0x7F // 0x4C, L
0x7F, 0x02, 0x04, 0x02, 0x7F // 0x4D, M
0x7F, 0x10, 0x08, 0x04, 0x7F // 0x4E, N
0x3E, 0x41, 0x41, 0x41, 0x3E // 0x4F, O
0x06, 0x09, 0x09, 0x09, 0x7F // 0x50, P
0x5E, 0x21, 0x51, 0x41, 0x3E // 0x51, Q
0x46, 0x29, 0x19, 0x09, 0x7F // 0x52, R
0x31, 0x49, 0x49, 0x49, 0x46 // 0x53, S
0x01, 0x01, 0x7F, 0x01, 0x01 // 0x54, T
0x3F, 0x40, 0x40, 0x40, 0x3F // 0x55, U
0x1F, 0x20, 0x40, 0x20, 0x1F // 0x56, V
0x7F, 0x20, 0x18, 0x20, 0x7F // 0x57, W
0x63, 0x14, 0x08, 0x14, 0x63 // 0x58, X
0x03, 0x04, 0x78, 0x04, 0x03 // 0x59, Y
0x43, 0x45, 0x49, 0x51, 0x61 // 0x5A, Z
0x41, 0x41, 0x7F, 0x00, 0x00 // 0x5B, [
0x20, 0x10, 0x08, 0x04, 0x02 // 0x5C, \
0x00, 0x00, 0x7F, 0x41, 0x41 // 0x5D, ]
0x04, 0x02, 0x01, 0x02, 0x04 // 0x5E, ^
0x40, 0x40, 0x40, 0x40, 0x40 // 0x5F, _
0x00, 0x04, 0x02, 0x01, 0x00 // 0x60, `
0x78, 0x54, 0x54, 0x54, 0x20 // 0x61, a
0x38, 0x44, 0x44, 0x48, 0x7F // 0x62, b
0x20, 0x44, 0x44, 0x44, 0x38 // 0x63, c
0x7F, 0x48, 0x44, 0x44, 0x38 // 0x64, d
0x18, 0x54, 0x54, 0x54, 0x38 // 0x65, e
0x02, 0x01, 0x09, 0x7E, 0x08 // 0x66, f
0x3C, 0x54, 0x54, 0x14, 0x08 // 0x67, g
0x78, 0x04, 0x04, 0x08, 0x7F // 0x68, h
0x00, 0x40, 0x7D, 0x44, 0x00 // 0x69, i
0x00, 0x3D, 0x44, 0x40, 0x20 // 0x6A, j
0x44, 0x28, 0x10, 0x7F, 0x00 // 0x6B, k
0x00, 0x40, 0x7F, 0x41, 0x00 // 0x6C, l
0x78, 0x04, 0x18, 0x04, 0x7C // 0x6D, m
0x78, 0x04, 0x04, 0x08, 0x7C // 0x6E, n
0x38, 0x44, 0x44, 0x44, 0x38 // 0x6F, o
0x08, 0x14, 0x14, 0x14, 0x7C // 0x70, p
0x7C, 0x18, 0x14, 0x14, 0x08 // 0x71, q
0x08, 0x04, 0x04, 0x08, 0x7C // 0x72, r
0x20, 0x54, 0x54, 0x54, 0x48 // 0x73, s
0x20, 0x40, 0x44, 0x3F, 0x04 // 0x74, t
0x7C, 0x20, 0x40, 0x40, 0x3C // 0x75, u
0x1C, 0x20, 0x40, 0x20, 0x1C // 0x76, v
0x3C, 0x40, 0x30, 0x40, 0x3C // 0x77, w
0x44, 0x28, 0x10, 0x28, 0x44 // 0x78, x
0x3C, 0x50, 0x50, 0x50, 0x0C // 0x79, y
0x44, 0x4C, 0x54, 0x64, 0x44 // 0x7A, z
0x00, 0x41, 0x36, 0x08, 0x00 // 0x7B, {
0x00, 0x00, 0x7F, 0x00, 0x00 // 0x7C, |
0x00, 0x08, 0x36, 0x41, 0x00 // 0x7D, }
0x08, 0x1C, 0x2A, 0x08, 0x08 // 0x7E, ~
0x08, 0x08, 0x2A, 0x1C, 0x08 // 0x7F, DEL
};
char led_buffer[50];
void max7221_fill_buffer(char *buffer) {
int i,j;
char *reverse_buffer,*led_buffer_ptr,currentchar;
j=strlen(buffer);
reverse_buffer[j--]=0;
for(i=0;i<strlen(buffer);i++,j--)
reverse_buffer[j]=buffer[i];
memset(led_buffer,0x00,50);
led_buffer_ptr=&led_buffer[0];
currentchar=*reverse_buffer;
while(currentchar) {
memcpy(led_buffer_ptr,font5x7[currentchar-0x20],5);
led_buffer_ptr+=5;
currentchar=*(++reverse_buffer);
}
}
void max7221_display_message() {
int column,index,dot_matrix;
for(column=DIGIT_0;column<=DIGIT_4;column++) {
index=5-column;
output_low(MAX7221_CS);
for(dot_matrix=1;dot_matrix<=MAX_DOT_MATRIX_USED;dot_matrix++) {
spi_write(column);
spi_write(led_buffer[index]);
index+=5;
}
output_high(MAX7221_CS);
}
}
void max7221_put(int addr,data) {
output_low(MAX7221_CS);
spi_write(addr);
spi_write(data);
output_high(MAX7221_CS);
}
void max7221_put_all(int addr,data) {
int dot_matrix;
output_low(MAX7221_CS);
for(dot_matrix=1;dot_matrix<=MAX_DOT_MATRIX_USED;dot_matrix++) {
spi_write(addr);
spi_write(data);
}
output_high(MAX7221_CS);
}
void max7221_blank_dot_matrix() {
int column;
for(column=DIGIT_0;column<=DIGIT_4;column++)
max7221_put_all(column,0x00);
}
void max7221_init() {
setup_spi(SPI_MASTER|SPI_L_TO_H|SPI_XMIT_L_TO_H|SPI_CLK_DIV_16);
max7221_put_all(DECODE_MODE,NO_DECODE_DIGITS_7_0);
max7221_put_all(SCAN_LIMIT,DISPLAY_DIGITS_01234);
max7221_put_all(SHUT_DOWN,NORMAL_MODE);
max7221_put_all(DISPLAY_TEST,NORMAL_OPERATION);
max7221_put_all(INTENSITY,DUTY_CYCLE_1);
}
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Last edited by The Puma on Thu Oct 11, 2007 11:44 am; edited 4 times in total |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 28, 2007 5:32 pm |
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| Quote: |
This is my code so far.
void main() {
setup_spi(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_16);
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Here are ckielstra's SPI mode definitions:
| Code: |
#define SPI_MODE_0_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_0_1 (SPI_L_TO_H)
#define SPI_MODE_1_0 (SPI_H_TO_L)
#define SPI_MODE_1_1 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
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From his definitions, we can see that you are using SPI mode 2.
("1_0" in binary is "2" in decimal).
Download the MAX7221 data sheet:
http://datasheets.maxim-ic.com/en/ds/MAX7219-MAX7221.pdf
In Figure 1 (on page 6), there is a timing diagram that shows the
relationship of CLK to DIN. It shows that the rising edge of CLK
is used to sample the data. The timing diagram also shows that
the CLK signal idles in the low state when it's not active. Both of
these things are needed to determine the correct SPI mode.
Now look at this diagram on the TotalPhase website.
http://www.totalphase.com/support/articles/article03/#modes
It shows the edge of the clock and the idle state of the clock,
that are used in each of the four possible SPI modes.
So here is a question for you:
Based on the information I gave you above, which SPI mode should
you use to communicate between the PIC and the Max7221 ?
How would you re-write your setup_spi() statement to use the
correct SPI mode ? |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 4:32 am |
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@PCM programmer
Which the setup_spi(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_16); the program works
with setup_spi(SPI_MASTER | SPI_L_TO_H | SPI_CLK_DIV_16) the output gives strange results.
Why??
I did't understand the above illustration you get.
Please can you give me the corrrect setup_spi command for the max7221 |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 11, 2007 11:24 am |
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Randomly trying different modes is not the way to solve the problem.
In the MAX7221 data sheet, they show the SPI timing in the diagram
with this title (on page 6):
| Quote: | | Figure 1. Timing Diagram |
http://datasheets.maxim-ic.com/en/ds/MAX7219-MAX7221.pdf
It shows the idle state of CLK is a low level, and that the Din signal
is sampled on the rising edge of CLK. Look at the diagram on the
Total Phase website, and it shows the SPI mode is clearly Mode 0.
That means you use this constant in the setup_spi():
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 11:38 am |
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Strange if a use your setting than the display give strange output.
Why did it work any good with setup, and with the SPI_H_L it work good?
Can you explain this?
setup_spi(SPI_MASTER|SPI_L_TO_H|SPI_XMIT_L_TO_H|SPI_CLK_DIV_16); |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 11, 2007 11:44 am |
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| What is the strange output ? Describe it. |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 11:48 am |
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See updated code above
If give one good character and then strange chars
If i use this setup, all works
setup_spi(SPI_MASTER|SPI_H_TO_L|SPI_CLK_DIV_16); |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 11, 2007 12:08 pm |
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| Quote: | | It gives one good character and then strange chars |
This probably means that the data is being delayed too much as
you pass it to several different MAX7221 chips. It's being delayed
so much that you have to invert the clock to make it work.
I haven't studied how to connect the MAX7221 chips in cascade mode,
but I suspect that you are not doing it correctly. |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 12:14 pm |
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Hardware:
The DOUT pin of the first chip is connected to the DIN pin ofr the second chip, and so on
All CLK and CS lines connected to all chips
Is the SPI_CLK_DIV_16 a good choice for this chip??
and must all chips get the initializing commands? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Oct 11, 2007 12:18 pm |
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It may be the CLK signal that's getting delayed too much. I'll have to
read the data sheet later. I don't have any more time right now. |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 2:05 pm |
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I have a unit with one max7221 on it
The max7221 is connected to eight 7 seven displays
Then works the setup_spi(SPI_MASTER|SPI_L_TO_H|SPI_XMIT_L_TO_H|SPI_CLK_DIV_16) without problems
Why is that possible?
Here is the code
| Code: |
#include <18F4620.h>
#use delay(clock=20000000)
#fuses HS,NOWDT,NOBROWNOUT,NOPUT,NOLVP,DEBUG,NOSTVREN,NOPROTECT
#include <max7221_et_sdp8.h>
void main() {
int32 j;
max7221_init();
max7221_blank_digits();
for(j=0;j<10000000;j++) {
max7221_write_num(j);
delay_ms(20);
}
}
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| Code: |
#ifndef MAX7221_CS
#define MAX7221_CS PIN_C0
#define MAX7221_CLK PIN_C3
#define MAX7221_DOUT PIN_C4
#define MAX7221_DIN PIN_C5
#endif
// Register address map
#define NO_OP 0x00 // Used when cascading max7221s
#define DIGIT_0 0x01 // Digit 0 register
#define DIGIT_1 0x02 // Digit 1 register
#define DIGIT_2 0x03 // Digit 2 register
#define DIGIT_3 0x04 // Digit 3 register
#define DIGIT_4 0x05 // Digit 4 register
#define DIGIT_5 0x06 // Digit 5 register
#define DIGIT_6 0x07 // Digit 6 register
#define DIGIT_7 0x08 // Digit 7 register
#define DECODE_MODE 0x09 // Decode mode register
#define INTENSITY 0x0A // Intensity register
#define SCAN_LIMIT 0x0B // Scan-limit register
#define SHUT_DOWN 0x0C // Shutdown register
#define DISPLAY_TEST 0x0F // Display-test register
// Shutdown register
#define SHUTDOWN_MODE 0x00 // Shutdown mode
#define NORMAL_MODE 0x01 // Normal mode
// Decode-mode register
#define NO_DECODE_DIGITS_7_0 0x00 // No decode for digits 7-0
#define CODE_B_DECODE_DIGIT_0 0x01 // Code B decode for digit 0
#define CODE_B_DECODE_DIGITS_3_0 0x0F // Code B decode for digits 3-0
#define CODE_B_DECODE_DIGITS_7_0 0xFF // Code B decode for digits 7-0
// Code B font
#define SEGMENT_CHAR_0 0x00 // 0
#define SEGMENT_CHAR_1 0x01 // 1
#define SEGMENT_CHAR_2 0x02 // 2
#define SEGMENT_CHAR_3 0x03 // 3
#define SEGMENT_CHAR_4 0x04 // 4
#define SEGMENT_CHAR_5 0x05 // 5
#define SEGMENT_CHAR_6 0x06 // 6
#define SEGMENT_CHAR_7 0x07 // 7
#define SEGMENT_CHAR_8 0x08 // 8
#define SEGMENT_CHAR_9 0x09 // 9
#define SEGMENT_CHAR_LINE 0x0A // -
#define SEGMENT_CHAR_E 0x0B // E
#define SEGMENT_CHAR_H 0x0C // H
#define SEGMENT_CHAR_L 0x0D // L
#define SEGMENT_CHAR_P 0x0E // P
#define SEGMENT_CHAR_BLANK 0x0F // BLANK
#define SEGMENT_CHAR_DP 0x80 // DP
// Intensity register
#define DUTY_CYCLE_1 0x00 // Intensity min
#define DUTY_CYCLE_2 0x01
#define DUTY_CYCLE_3 0x02
#define DUTY_CYCLE_4 0x03
#define DUTY_CYCLE_5 0x04
#define DUTY_CYCLE_6 0x05
#define DUTY_CYCLE_7 0x06
#define DUTY_CYCLE_8 0x07
#define DUTY_CYCLE_9 0x08
#define DUTY_CYCLE_10 0x09
#define DUTY_CYCLE_11 0x0A
#define DUTY_CYCLE_12 0x0B
#define DUTY_CYCLE_13 0x0C
#define DUTY_CYCLE_14 0x0D
#define DUTY_CYCLE_15 0x0E
#define DUTY_CYCLE_16 0x0F // Intensity full
// Scan-limit register
#define DISPLAY_DIGIT_0 0x00 // Display digit 0
#define DISPLAY_DIGITS_01 0x01 // Display digits 0 & 1
#define DISPLAY_DIGITS_012 0x02 // Display digits 0 1 2
#define DISPLAY_DIGITS_0123 0x03 // Display digits 0 1 2 3
#define DISPLAY_DIGITS_01234 0x04 // Display digits 0 1 2 3 4
#define DISPLAY_DIGITS_012345 0x05 // Display digits 0 1 2 3 4 5
#define DISPLAY_DIGITS_0123456 0x06 // Display digits 0 1 2 3 4 5 6
#define DISPLAY_DIGITS_01234567 0x07 // Display digits 0 1 2 3 4 5 6 7
// Display-test register
#define NORMAL_OPERATION 0x00 // Normal operation
#define DISPLAY_TEST_MODE 0x01 // Display-test mode, all leds on
void max7221_put(int addr,data) {
output_low(MAX7221_CS);
spi_write(addr);
spi_write(data);
output_high(MAX7221_CS);
}
void max7221_write_num(int32 num) {
int1 leading=true;
int8 led_data[8];
int8 j;
int32 temp32;
for(j=0;j<7;j++) {
temp32=num/10;
led_data[j]=num-(temp32*10);
num=temp32;
}
led_data[7]=num;
for(j=7;j>0;j--) {
if(leading&&led_data[j]==0)
led_data[j]=SEGMENT_CHAR_BLANK;
else
leading=false;
}
for(j=DIGIT_0;j<=DIGIT_7;j++)
max7221_put(j,led_data[j-1]);
}
void max7221_blank_digits() {
int j;
for(j=DIGIT_0;j<=DIGIT_7;j++)
max7221_put(j,SEGMENT_CHAR_BLANK);
}
void max7221_init() {
setup_spi(SPI_MASTER|SPI_L_TO_H|SPI_XMIT_L_TO_H|SPI_CLK_DIV_16);
max7221_put(DECODE_MODE,CODE_B_DECODE_DIGITS_7_0);
max7221_put(SCAN_LIMIT,DISPLAY_DIGITS_01234567);
max7221_put(SHUT_DOWN,NORMAL_MODE);
max7221_put(INTENSITY,DUTY_CYCLE_4);
}
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Thu Oct 11, 2007 3:44 pm |
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I have tested futher and it is an no go with L_TO_H
This simple example lit on every column of the dot matrix from above to below an led
With H_TO_L it work OK, with L_TO_H it gives problems
| Code: | void main() {
int i,j;
max7221_init();
max7221_blank_dot_matrix();
while(TRUE) {
for(j=DiGIT_0;j<=DIGIT_4;j++) {
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(1);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(2);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(4);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(8);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(16);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(32);
}
output_high(MAX7221_CS);
delay_ms(100);
output_low(MAX7221_CS);
for(i=1;i<=10;i++) {
spi_write(j);
spi_write(64);
}
output_high(MAX7221_CS);
delay_ms(100);
max7221_blank_dot_matrix();
}
}
} |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Oct 14, 2007 5:37 pm |
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| The MAX7221 data sheet shows that the SPI timing is setup for Mode 0,0. |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Mon Oct 15, 2007 1:26 am |
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strange, in the datasheet Using Maxim SPI-compatible Display Drivers with other SPI Peripherals shows that it must as follows
CPHA=1
CPOL=0
Please can you tell me what the Setup_Spi for that is? |
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