I experienced the same problem, and apparently the chip never was able to update the wiper position.
Reading back data by read command, after write wiper was ok, but still no changes.
All was apparently correct, after I spent about 6 hours to change all what possible and become frustrating I have read again carefully the datasheet....
The solution was quite simple!
First the correct mode of SPI needs to be actuated to follow datasheet
(for instance must be specified that the spi interface accept several modes and not so critical):
1) CLOCK MUST BE ->LOW IDLE
2) CLOCK SELECT ->FALLING EDGE
3) BE SURE THAT /SYNC PIN MUST BE DRIVEN LOW BEFORE CLOCK STARTS (FROM LOW IDLE TO HIGH)
Now the simple one :
4) READ CAREFULLY TABLE 12 of datasheet that is page 23 if Rev.A document
The story is : SEND FIRST HEX 1803 to enable wiper position
Then if want update wiper : SEND COMMAND 1 (TABLE 11)
Then if want verify : SEND COMMAND 7
Conclusion
Before wiper and / or 20TP memory may be updated HEX 1803 must be sended to DAC register, then this DAC works perfectly!.
*PS (I Hope must be helpful)
Aldo Ferraro - CONSULTANT
ELDEV ELETTRONICA
MILANO
Hi, I'm trying to use an AD5291 as a variable resistor for the variable gain in a signal generator board, it's not working at all, and even if I try to initialize it with different values it just uses the default value (half of the nominal resist value).
This is my init pot function:
void spi_init_pot()
{
uint8 i, tmp;
uint8 init_data[] = {0x18,0x03,0x05,0x00,0x08,0x00,0x0c,0x00,0x1c,0x00,0x00,0x00};
for (i=0; i<6; i++)
{
SS_POT = 0; // Slave select 0
SS_POT_DIR = 1;
SPI2D = init_data[(i*2)]; // 2 bytes of data
while (!SPI2S_SPTEF || !SPI2S_SPRF) // FF - max out (VDD)
tmp = SPI2D; // 00 - min out (GND)
SPI2D = init_data[1 + (i*2)]; // 2 bytes of data
while (!SPI2S_SPTEF || !SPI2S_SPRF) // FF - max out (VDD)
tmp = SPI2D; // 00 - min out (GND)
SS_POT = 1; // Slave select 1
SS_POT_DIR = 0;
}
}
This is my setting different value function:
void spi_set_pot(RX_msg_struct *t)
{
uint8 i, temp;
if((t->D_Len - 0x03) == 0x02)
{
SS_POT = 0; // Slave select 0. modified by Bellina
SS_POT_DIR = 1;
for (i=0; i<2; i++)
{
SPI2D = t->DB
; // 2 bytes of data
while (!SPI2S_SPTEF || !SPI2S_SPRF) // FF - max out (VDD)
temp = SPI2D; // 00 - min out (GND)
}
SS_POT = 1; // Slave select 1
SS_POT_DIR = 0; // modified by Bellina
}
}