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StuH_CC
Joined: 07 May 2004
Posts: 16
Location: Shropshire, UK
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| MAX6953 5x7 LED matrix driver functions |
 Posted: Tue Aug 10, 2004 6:23 pm |
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I hope this isn't too messy! It works, anyway (if I haven't left something out...).
| Code: | /******************************************************************************
Driver routines for MAX6953 5x7 cathode-row LED display drivers.
Written for the CCS PCM cross-compiler version 3.185
Originally written by Stuart Hunter, Technical Director, ViziMatic Ltd.
******************************************************************************/
#ifndef DISPLAY_SDA
//The pin definitions are set for a PIC16F819 SSP module. If they are
//redefined elsewhere before this file is included then your own definitions
//will override these.
#define DISPLAY_SDA PIN_B1
#define DISPLAY_SCL PIN_B4
#endif
//Miscellaneous defines
#define SLOW 0 //Use for setting blink rate
#define FAST 1
#define PLANE0 0x20 //Use for setting data start address
#define PLANE1 0x40
#define BOTHPLANES 0x60
#define WRITE_NOW 1 //Used in operations affecting the CONFIG
#define WRITE_LATER 0 //register.
//Add FORCE_HW to the end of the line below if you want or need
//to use a hardware I2C implementation (ie your PIC has the MSSP module).
//Remove the line if you've already defined the I2C pins!!!
#use i2c(master, sda=DISPLAY_SDA, scl=DISPLAY_SCL ) //,FORCE_HW
int config_byte;
int device_address;
// Initialise the I2C bus and config register
void init_display()
{
output_float(DISPLAY_SCL);
output_float(DISPLAY_SDA);
config_byte = 0;
}
void set_device_address( int addr )
{
addr+= 0x50; //MAX6953 addresses take the form 101xxxx
device_address = addr; //where xxxx is the user-selected address 0-15.
}
// This function is mainly for internal use, but you can use it to
// set the CONFIG register directly if you don't want to use the
// individual functions provided for this purpose.
void write_config_register( int config_byte )
{
i2c_start();
i2c_write( (device_address<<1) & 0xFE );
i2c_write( 0x04 );
i2c_write( config_byte );
i2c_stop();
}
// This function sets the display interval for each display plane.
// With a 4MHz clock, FAST is 0.5s and SLOW is 1.0s.
void set_blink_speed( int speed, short wrt )
{
if( speed == SLOW ) config_byte &= 0xFB;
else config_byte |= 0x04;
if( wrt ) write_config_register( config_byte );
}
// This function enables or disables plane switching ( blinking )
void blink_enable( short state, short wrt )
{
if( state ) config_byte |= 8;
else config_byte &= 0xF7;
if( wrt ) write_config_register( config_byte );
}
// This function is used for blink time synchronisation across multiple devices.
// call it once for each device, in sequence. Nonpersistent.
void blink_sync( void )
{
write_config_register( config_byte |= 0x10 );
}
// Clear the plane data in the chip. Nonpersistent.
void clear_digits( void )
{
write_config_register( config_byte | 0x20 );
}
// Put the display into low power shutdown mode
void shutdown( short state, short wrt )
{
if( !state ) config_byte |= 0x01;
else config_byte &= 0xFE;
if( wrt ) write_config_register( config_byte );
}
// Put the display in test mode. Will illuminate all LEDs if state=TRUE.
// Does not affect plane data - original display is restored when set FALSE.
void display_test( short state )
{
i2c_start();
i2c_write( (device_address<<1) & 0xFE );
i2c_write( 0x07 );
if (state )
{
i2c_write( 1 );
}
else
{
i2c_write( 0 );
}
i2c_stop();
}
// Set the display intensity from 0-15. This routine sets all digits to
// the same value, if you want to set 'em individually then you need to
// implement your own function - I don't need that ability!
void set_intensity( int intens )
{
int tempd;
tempd = intens<<4; //set the most significant nybble
intens |= tempd;
i2c_start();
i2c_write( (device_address<<1) &0xFE );
i2c_write( 0x01 ); //first intensity register
i2c_write( intens );
i2c_write( intens ); //register addr autoincrements, so write second reg.
i2c_stop();
}
// Sets the number of digits to be displayed ( 2 or 4 ). Included just for
// the hell of it - I don't use this in my app.
void set_scan_limit( short state )
{
i2c_start();
i2c_write( (device_address<<1) &0xFE );
i2c_write( 0x03 );
if (state )
{
i2c_write( 1 );
}
else
{
i2c_write( 0 );
}
i2c_stop();
}
// Set the plane data for display. Normal characters should be written to
// PLANE0. See the Maxim datasheet for an explanation of the data planing
// system.
void write_display_character( int start, int length, char* string )
{
int n;
i2c_start();
i2c_write( (device_address<<1) &0xFE );
i2c_write( start ); //start address of write operation
for( n=0; n<length; n++ )
{
i2c_write( string[n] ); //write noninverted string, address
} //will autoincrement.
i2c_stop();
}
// As above, but displays an inverted ( background lit, char off ) character.
void write_inverted_display_character( int start, int length, char* string )
{
int n;
i2c_start();
i2c_write( (device_address<<1) &0xFE );
i2c_write( start ); //start address of write operation
for( n=0; n<length; n++ )
{
i2c_write( string[n] |= 0x80 ); //write inverted string, address
} //will autoincrement.
i2c_stop();
}
|
As an example, in the main() function, include the following code:
| Code: |
init_display();
set_device_address( 0 );
shutdown( FALSE,TRUE );
set_intensity( 15 );
display_test( TRUE );
delay_ms( 2000 );
display_test( FALSE );
write_display_character( PLANE0,4,"TEST" );
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This of course assumes that your MAX6953 is set at the base address - if it isn't, then substitute the appropriate number 0-15 in set_device_address(). |
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The Puma
Joined: 23 Apr 2004
Posts: 227
Location: The Netherlands
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| Posted: Tue Feb 28, 2006 1:07 pm |
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Is the driver the same for the MAX6952, exept then the I2C functions
this must be concerted to SPI |
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Fri May 18, 2007 12:15 pm |
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Hello!
I am trying to use the previous driver but I have some problems with the program. The MPLAB gives me that error:
Error 90 "E:\MPLAB 7.50\Projects\... …" Line 24(43,44): Attempt to create a pointer to a constant
And the program is:
#include <16F876A.h>
#fuses XT, NOWDT, NOPUT, NOPROTECT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
#use delay (clock = 4000000)
#include <max6953.c>
void main()
{
input(pin_b2);
input(pin_b3);
input(pin_c0);
input(pin_c1);
delay_ms(100);
output_high(pin_a5);
init_display();
set_device_address( 0 );
shutdown( FALSE,TRUE );
set_intensity( 1 );
display_test( TRUE );
delay_ms( 2000 );
display_test( FALSE );
write_display_character( PLANE0,4, "TEST" ); ---------------------Error
while(1)
{
output_high(pin_a5);
delay_ms(1000);
output_low(pin_a5);
delay_ms(1000);
}
}
What I have to do??? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri May 18, 2007 12:32 pm |
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Create an array in RAM. Copy the constant string into that array.
Pass the array to the write_display_character() function. See the
changes shown in bold below:
| Quote: |
void main()
{
char stringbuf[20];
.
.
.
strcpy(stringbuf, "TEST");
write_display_character( PLANE0, 4, stringbuf);
.
.
.
while(1);
} |
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Lykos1986
Joined: 26 Nov 2005
Posts: 68
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| Posted: Fri May 18, 2007 2:48 pm |
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It works!!!!!
Thank you very much!!!
But why that is happening? I have very basics knowledge on C |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri May 18, 2007 3:01 pm |
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Read the compiler error message:
| Quote: | | Line 24(43,44): Attempt to create a pointer to a constant |
The compiler will not let you create a pointer to a string stored in ROM.
It will only let you create a pointer to a string stored in RAM.
Therefore, you must copy the string from a ROM array ('const') to
a RAM array. Then you can pass the RAM array to a function.
This is a limitation of CCS with the PIC. In future versions of CCS,
they propose to remove this limitation. |
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getforumcss
Joined: 03 Jun 2007
Posts: 1
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| Posted: Sun Jun 03, 2007 3:44 pm |
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Tks you StuH_CC
It is a very good sample code! but you don't have implement all functionality of a max6953 eg for using USER-DEFINED Fonts in address code 0x05.
i would like drawn a heart or several smiler. can you make it...
best regard
getelectronic |
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