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andibaciu
Joined: 06 Feb 2006
Posts: 6
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| MAX5821 some problems ... help |
 Posted: Thu Aug 09, 2007 11:21 pm |
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I want to communicate with 1 MAX5821 - i2c communication, 10bit DAC, voltage output and i have some problems .... If somebody could help me i'll appreciate.
for MAX5821 i write a driver:
| Code: |
// MAX5821M.c -- Dual 10 bit Voltage Output DAC
// MAX5821 commands
#define MAX5821_CMD_LOAD_DAC_A_UPDATE 0x00
#define MAX5821_CMD_LOAD_DAC_B_UPDATE 0x10
#define MAX5821_CMD_LOAD_DAC_A_NOUPDATE 0x40
#define MAX5821_CMD_LOAD_DAC_B_NOUPDATE 0x50
#define MAX5821_CMD_UPDATE_ALL_LOAD_DAC_A 0x80
#define MAX5821_CMD_UPDATE_ALL_LOAD_DAC_B 0x90
#define MAX5821_CMD_LOAD_ALL_UPDATE_ALL 0xC0
#define MAX5821_CMD_LOAD_ALL_NOUPDATE 0xD0
#define MAX5821_CMD_UPDATE_ALL_NO_D9_D6 0xE0 //no more OR opperation
#define MAX5821_CMD_POWER_DOWN_MODE 0xF0 //no more OR opperation
#define MAX5821_CMD_READ_DAC_A 0xF1 //no more OR opperation
#define MAX5821_CMD_READ_DAC_B 0xF2 //no more OR opperation
#define MAX5821_POWER_UP 0x00 //Start device.
#define MAX5821_POWER_DOWN_MODE_1 0x01 //high impedance; output floating
#define MAX5821_POWER_DOWN_MODE_2 0x02 //pulled to GND by 1Kohm
#define MAX5821_POWER_DOWN_MODE_3 0x03 //pulled to GND by 100Kohm
#define MAX5821_DEVICE_ADDRESS_1 0xB0 //MAX5821M with ADD connected to GND
#define MAX5821_DEVICE_ADDRESS_2 0xB2 //MAX5821M with ADD connected to Vdd
//======================================
void MAX5821_init(int address,int dac, int power_mode)
{
int mode=0;
i2c_start();
i2c_write(address);
i2c_write(MAX5821_CMD_POWER_DOWN_MODE);
if(dac==1)
mode=power_mode|0x04;
if(dac==2)
mode=power_mode|0x08;
i2c_write(mode);
i2c_stop();
}
void MAX5821_cmd_dac(int address,int command,int16 value)
{
int val1,val2;
int16 temp;
temp=value;
val1=temp>>6;
val1=command|val1;
temp=value;
val2=temp;
val2=val2<<2;
i2c_start();
i2c_write(address);
i2c_write(val1);
i2c_write(val2);
i2c_stop();
}
void MAX5821_write_dac(int address,int dac,int16 value)
{
int val1,val2;
int16 temp;
temp=value;
temp=shift_right(temp,6,0);
val1=make8(temp,0);
val1=val1&0x0F;
if(dac==1)
val1=MAX5821_CMD_LOAD_DAC_A_UPDATE|val1;
if(dac==2)
val1=MAX5821_CMD_LOAD_DAC_B_UPDATE|val1;
temp=value;
temp=shift_left(temp,2,0);
val2=make8(temp,0);
val2=val2&0xFC;
i2c_start();
i2c_write(address);
i2c_write(val1);
i2c_write(val2);
i2c_stop();
}
int MAX5821_read_dac_power_mode(int address,int dac)
{
int val1,val2;
i2c_start();
i2c_write(address);
if(dac==1)
i2c_write(MAX5821_CMD_READ_DAC_A);
if(dac==2)
i2c_write(MAX5821_CMD_READ_DAC_B);
i2c_start();
i2c_write(address+1);
val1=i2c_read();
val2=i2c_read(0);
i2c_stop();
val1=val1<<2;
val1=val1>>6;
return val1;
}
int16 MAX5821_read_dac_value(int address,int dac)
{
int val1,val2;
int16 value;
i2c_start();
i2c_write(address);
if(dac==1)
i2c_write(MAX5821_CMD_READ_DAC_A);
if(dac==2)
i2c_write(MAX5821_CMD_READ_DAC_B);
i2c_start();
i2c_write(address+1);
val1=i2c_read();
val2=i2c_read(0);
i2c_stop();
val1=val1<<4;
val1=val1>>4;
value=make16(val1,val2);
value=value>>2;
return value;
}
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and to call this driver i write a little program where i put:
| Code: |
MAX5821_init(MAX5821_DEVICE_ADDRESS_1,1,MAX5821_POWER_UP);
MAX5821_init(MAX5821_DEVICE_ADDRESS_1,2,MAX5821_POWER_UP);
delay_ms(10);
MAX5821_write_dac(MAX5821_DEVICE_ADDRESS_1,2,0);
MAX5821_write_dac(MAX5821_DEVICE_ADDRESS_1,1,0);
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when i start with this code all things are ok ... but when i try to set some value in DAC registers:
| Code: |
MAX5821_write_dac(MAX5821_DEVICE_ADDRESS_1,2,xxx);
MAX5821_write_dac(MAX5821_DEVICE_ADDRESS_1,1,xxx);
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my program crash and stop.
Could somebody help me to solve this problem ? or maybe somebody already have a good driver for MAX5821and want to share.
Thanks! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Aug 10, 2007 12:03 am |
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| Quote: | void MAX5821_write_dac(int address,int dac,int16 value)
{
int val1,val2;
int16 temp;
temp=value;
temp=shift_right(temp,6,0);
val1=make8(temp,0);
val1=val1&0x0F;
if(dac==1)
val1=MAX5821_CMD_LOAD_DAC_A_UPDATE|val1;
if(dac==2)
val1=MAX5821_CMD_LOAD_DAC_B_UPDATE|val1;
temp=value;
temp=shift_left(temp,2,0);
val2=make8(temp,0);
val2=val2&0xFC;
i2c_start();
i2c_write(address);
i2c_write(val1);
i2c_write(val2);
i2c_stop();
} |
The two lines with the shift functions have problems.
1. The first parameter must be the address of a variable or an array.
'temp' is an int16, so if you want pass the address of temp, you
must do it like this:
2. The middle parameter is the number of bytes that are to be involved
in the shift operation. 'temp' is only 2 bytes, so the middle parameter
should be 2, at most. It can't be 6. The shift functions only do a
shift of 1 bit position per call. This is in the manual.
3. The shift functions only return a value of 1 or 0. They don't return
the complete shifted variable.
I didn't look at the program in detail. There might be other problems. |
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andibaciu
Joined: 06 Feb 2006
Posts: 6
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| Posted: Fri Aug 10, 2007 12:45 am |
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Thanks PCM programmer ...
I think I made a big confusion between shift_right and >> and between shift_left and <<.
so .. in my case my function must be:
| Code: |
void MAX5821_write_dac(int address,int dac,int16 value)
{
int val1,val2;
int16 temp;
temp=value;
temp=temp>>6;
val1=make8(temp,0);
val1=val1&0x0F;
if(dac==1)
val1=MAX5821_CMD_LOAD_DAC_A_UPDATE|val1;
if(dac==2)
val1=MAX5821_CMD_LOAD_DAC_B_UPDATE|val1;
temp=value;
temp=temp<<2;
val2=make8(temp,0);
val2=val2&0xFC;
i2c_start();
i2c_write(address);
i2c_write(val1);
i2c_write(val2);
i2c_stop();
}
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so... in this case I must make a new test ....
I'll keep you inform about my problem ... |
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