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pic_micro
Joined: 07 Feb 2011
Posts: 26
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| Upload custom character to MAX7456 chip |
 Posted: Thu Apr 21, 2011 10:14 pm |
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I used the MAX7456 dev kit GUI to create custom character, after I save it into *.MCM file, I open with notepad and there is 16385 lines, here are some of the top lines
MAX7456
1010101
1010101
1010101
1010101
1010101
1010101
1010101
1010101
1010101
1010101
1010101
.
.
.
to 16385 lines total.
How can I upload these to the MAX7456 chip?
I follow John Geek links http://www.john.geek.nz/2011/01/adding-custom-characters-to-the-max7456-video-overlay-generator/
But according to his, there will be only 54 lines to upload (0-53). I not sure what to do. Can anybody help?
Remember, I build my own board (breadboard) according to SparkFun schematic, so there is no way I can access the chip as describe per Maxim kits through Serial or USB. |
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temtronic
Joined: 01 Jul 2010
Posts: 9229
Location: Greensville,Ontario
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| Posted: Fri Apr 22, 2011 6:07 am |
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John's article clearly details how to create and upload the custom characters.Simple and easy.His code can be converted to CCS C in a few minutes.
So how does your PIC communicate with the MAX7456 if not through SPI ? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19518
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| Posted: Fri Apr 22, 2011 8:56 am |
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To emphasise the point, look at the chip's data sheet. It's _only_ interface, is SPI. Serial peripheral interface. The demo boards allowing you to access the chip using other interfaces, have a processor like the PIC, receiving data from USB or RS232, and then talking to the chip. Exactly what you can do with a PIC.
Best Wishes |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Apr 22, 2011 1:32 pm |
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| Quote: | How can I upload these to the MAX7456 chip?
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You gave up on your other MAX7456 thread, here:
http://www.ccsinfo.com/forum/viewtopic.php?t=45241
Did you ever do the test to see if you can read back the same byte that
you wrote to the chip ? You need to do that before you try anything else.
With regard to the John Geek link, he's using "spi_send_byte()" to send
the data to the MAX7456. That's equivalent to the max7456_write()
function, shown in the code below.
To do the communication test with the MAX7456, connect your PIC to the
Max7456 like this:
| Code: |
PIC Max7456
SDO SDIN
SDI SDOUT
SCLK SCLK
\CS \CS
|
Use pin C2 on the PIC for \CS.
Then run this program. It should hopefully say that it read "55" from
the MAX7456:
| Code: |
#include <16F877A.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
// SPI mode definitions.
#define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_1 (SPI_L_TO_H)
#define SPI_MODE_2 (SPI_H_TO_L)
#define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
#define MAX7456_CS PIN_C2
//-------------------------------------
// Write to the specified register.
void max7456_write(int8 reg_addr, int8 data)
{
output_low(MAX7456_CS);
spi_write(reg_addr);
spi_write(data);
output_high(MAX7456_CS);
}
//------------------------------------
// Read the specified register.
int8 max7456_read(int8 reg_addr)
{
int8 retval;
output_low(MAX7456_CS);
spi_write(reg_addr | 0x80); // Set top bit to do a Read operation
retval = spi_read(0);
output_high(MAX7456_CS);
return(retval);
}
//======================================
void main()
{
int8 result;
// Initialize the PIC's SPI module.
setup_spi(SPI_MASTER|SPI_MODE_0|SPI_CLK_DIV_4);
output_high(MAX7456_CS);
delay_ms(100); // Minimum power-up delay is 50 ms
max7456_write(0, 0x55); // Write 0x55 to register 0
result = max7456_read(0); // Read register 0
// Display what we read.
printf("Wrote 0x55, read: %X \n\r", result);
while(1);
}
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pic_micro
Joined: 07 Feb 2011
Posts: 26
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| MAX7456 GRAPHIC |
| Posted: Thu Apr 28, 2011 9:49 am |
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I got it working by using SPI function like you mentioned earlier. I can send characters to MAX7456 and display it OK.
I am trying to display clock ( HH:MM:SS or 12:59:59 on the the screen (number 0-9 only, no character), but I can't figure out how to convert hex to decimal to display on the screen. When I increment the SEC, MIN, HOUR, they are in hex format not decimal, example e.g instead of hex 0x0A, 0x0B .... 0x3F , I want 10, 11, .... 59 to display
I have int SEC, MIN, HOUR; and I also define location to display char xSEC, xMIN, xHOUR.
I use timer1 interrupt and start increase SEC, MIN, HOUR
if SEC >= 59, reset SEC = 0 and increment MIN, if MIN >= 59, reset MIN = 0 and increment HOUR, and etc.
What is the best way to convert HEX to DEC? is there any sample code to handle this?
below are my code:
max.c (main)
| Code: | #include <16f877a.h>
#fuses XT, NOWDT, NOPROTECT, NOBROWNOUT, NOPUT, NOLVP
#use delay(clock=4000000)
/************************
connection
PIC | MAX7456
----------------
16 | 11 - C4
15 | 9 - C5
14 | 10 - C3
| 8 - A1
**************************/
#include <driver.c>
#include <interrupts.c>
void main()
{
max7456_init();
max7456_write(0x00, 0x02);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_4);
enable_interrupts(INT_TIMER1);
enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);
while(1)
{
}
} |
driver.c
| Code: | #define MAX7456_CS PIN_A1
#define MAX7456_CLK PIN_C3
#define MAX7456_DI PIN_C5
#define MAX7456_DO PIN_C4
char x = 0;
void max7456_write(int8 addr, int8 data)
{
output_low(MAX7456_CS);
spi_write(addr);
spi_write(data);
output_high(MAX7456_CS);
delay_ms(1);
}
//============= Disable ========================
void Disable(void) // Disable
{
max7456_write(0x00, 0x00);
}
//============= Enable =======================
void Enable(void)
{
max7456_write(0x00, 0x08); // Enable NTSC
max7456_write(0x04, 0x40);
}
//============= Enable =======================
void max7456_init(void)
{
short int i;
output_low(MAX7456_DI);
output_low(MAX7456_CLK);
output_high(MAX7456_CS);
i=input(MAX7456_DO);
setup_spi(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_16);
}
void lines(void)
{
enable();
// =========LINE1 ============
x = 1;
max7456_write(0x06, x);
max7456_write(0x07, 0x01);
delay_ms(10);
// =========LINE2 ============
x = 31;
max7456_write(0x06, x);
max7456_write(0x07, 0x02);
delay_ms(10);
// =========LINE3 ============
x = 61;
max7456_write(0x06, x);
max7456_write(0x07, 0x03);
delay_ms(10);
// =========LINE4 ============
x = 91;
max7456_write(0x06, x);
max7456_write(0x07, 0x04);
delay_ms(10);
// =========LINE5 ============
x = 121;
max7456_write(0x06, x);
max7456_write(0x07, 0x05);
delay_ms(10);
// =========LINE6 ============
x = 151;
max7456_write(0x06, x);
max7456_write(0x07, 0x06);
delay_ms(10);
} |
interrupts.c
| Code: | int counter = 0;
int MIN = 0;
int SEC = 0;
int HOUR = 0;
char xHour = 40;
char xMIN = 45;
char xSEC = 50;
void display(void)
{
max7456_write(0x06, xHOUR);
max7456_write(0x07, HOUR);
delay_ms(1);
max7456_write(0x06, xMIN);
max7456_write(0x07, MIN);
delay_ms(1);
max7456_write(0x06, xSEC);
max7456_write(0x07, SEC);
delay_ms(1);
}
}
#INT_TIMER1
timer1_isr()
{
clear_interrupt(INT_TIMER1);
counter++;
enable();
if(counter >=10)
{
SEC++;
if(SEC >= 0x3B) // decimal 59
{
SEC = 0;
MIN++;
if(MIN >= 0x3B) // decimal 59
{
HOUR++;
if(HOUR >= 0x0C) // decimal 12
{
HOUR = 0;
}
}
}
display();
}
}
#INT_EXT
void ext_ISR(void)
{
// clear screen
// clear_interrupt(INT_EXT);
max7456_write(0x00, 0x02);
delay_ms(20);
} |
If anyone can help me out, I would be appreciate |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Apr 28, 2011 11:08 am |
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Clock numbers are displayed in BCD format. You need a routine to
convert your byte integers to BCD. Here it is:
| Code: |
//----------------------------------------------
// This function converts an 8 bit binary value
// to an 8 bit BCD value.
// The input range must be from 0 to 99.
int8 bin2bcd(int8 value)
{
char retval;
retval = 0;
while(1)
{
// Get the tens digit by doing multiple subtraction
// of 10 from the binary value.
if(value >= 10)
{
value -= 10;
retval += 0x10;
}
else // Get the ones digit by adding the remainder.
{
retval += value;
break;
}
}
return(retval);
} |
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