![]() ![]() In reality, the SPI write was the most urgent.ġ. So all that is left is to debug the SPI read. > What is the minimum that I must do to just get a sinewave out- any frequency at all for my 25MHz crystal?Īll the code needs to do to get an output is enable a channel in CSR reg0 and write to FTW reg4. It is not supposed to have the bar on top. On the eval board schematic at page 24 it shows RESET with a bar on the top. The reset must be low for the chip to run in active mode. I put the software on a PC with Windows XP. In the eval board software, it warns about this. The crystal or the oscillator module must be running for the DDS to accept SPI commands. I lowered my SPI clock rate, but I don't think there was any need for that. It does not appear in my logic analyzer traces. The problem was that I did not drive SYNC_IO on SDIO_3 pin 53 at 0V. I got the DDS to produce sinusoids at the outputs. I did not get the read the work in 3 wire SPI mode. Is my chip dead? Am I stuck in the default SPI that bi-directional? What is the minimum that I must do to just get a sinewave out- any frequency at all for my 25MHz crystal? I saw posts of people who used both SPI modes 0 and 3. I tried the other SPI modes 1,2,3 without improvement. Read = SPI.transfer (0) /*bit7=1: Frank channel 1 enable only*/ĭigitalWrite(slaveSelectPinLmh6517, HIGH) SPI.transfer (0x83) //read to CSR (Channel Select Register) SPI.transfer (0x80) //read to CSR (Channel Select Register) SPI.transfer (0x00) //write to CSR (Channel Select Register)ĭigitalWrite(slaveSelectPinAd9958, HIGH) Please note, I have another chip that is sharing the MISO. When I didn’t have the 12k pull down it floated high. It is supposed to be at power up non-zero. I read that it is necessary to pulse the IO UPDATE for the serial mode to change. What does OPEN mean? I took the value 0xF2 from this post on this forum. I don’t understand the meaning of OPEN of the table on page 36. I send on MOSI instruction 0x00 which is write to register 0 (CSR). I made a capture of my SPI communication. Before without the pulldown, it was floating up to logic high. I put a 12k pull down resistor on SDIO_2, which MISO. I like to use single bit serial 3 wire mode as shown on page 33. ![]() (I keep it LOW.) Is it correct to have the reset low? I have the following logic levels on these pins: I can’t read on MISO and I can’t get the chip to produce anything on the sinusoid outputs. I have the AD9958 of a board of my own design with 25MHz crystal temporarily hooked up to an Arduino. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |