Part Number: DAC81408EVM
I have problem writing to the configuration registers on DAC81408. I can read the registers but cannot write to it.
For example, when I send the command 0x83000000 through the SPI interface, I can read the (SPICONFIG register)
data back as 0xXX0AA4XX. When I send the command 0x030A84000, I expect to to write "0A84" to the
register but it doesn't. The data I read back is still "0AA4". Is there any thing I should do to enable writing
to the registers?
Lap
Hi Paul,
I am using the TI C2000 Delfino MCU F28379D LaunchPad™ development kit to generate the SPI signal. I can successfully
control the DAC80508EVM. However, once I changed to the DAC81408EVM, I cannot write to the configuration registers.
The following pictures depicts the two commands I sent through the SPI:
SpiaRegs.SPITXBUF = 0x8300; // read operation to SPICONFIG register (first access cycle)
SpiaRegs.SPITXBUF = 0x0000; // second half of the 32-bit data
while (SpiaRegs.SPIFFRX.bit.RXFFST != 2) {} // two words has received -> done
*rr = SpiaRegs.SPIRXBUF; // removal of the 1st received words
*(rr+1) = SpiaRegs.SPIRXBUF; // removal of the 2nd received words
SpiaRegs.SPITXBUF = 0x8300; // read operation to SPICONFIG register (second access cycle)
SpiaRegs.SPITXBUF = 0x0000; // second half of the 32-bit data
while (SpiaRegs.SPIFFRX.bit.RXFFST != 2) {} // two words has received -> done
*rr = SpiaRegs.SPIRXBUF; // removal of the 1st received words
*(rr+1) = SpiaRegs.SPIRXBUF; // removal of the 2nd received words
The data I get back from the read operation (second access cycle) is 0x800AA483. The "0AA4" is the default data for the SPICONFIG register. One of
the problem is that I am expecting to get 0x830AA4XX instead of 0x800AA4XX (X: don't care). Another question is that I am using the 24-bit SPI access
but the LaunchPad kit only allows sending 16-bit data (am I right?). Therefore, I send two 16-bit data and the DAC should automatically ignore the last
8 bits of data.
Now, If I send the write operation 0x030A8400 to the DAC, the SPICONFIG register is still "0AA4" not "0A84". I am thinking this maybe the 24-bit/32-bit
access problem. Please help.
Thank you.
Lap
