Hi,
I called TI support and they suggested I ask the E2E community.
I'm trying to program the registers of a LM96570 chip I purchased. I'm having issues programming the chip as I desire. I was wondering if there is a MINIMUM frequency at which the serial clock must use, as it is not specified on the datasheets. I would assume that there is not, and that data is only latched on the rising edge of the serial clock, as long as the serial LatchEnable is kept low throughout.
As I do not have access readily to an FPGA, I created a simple Arduino program to program the LM96570 using the Arduino Due's SPI library.
The problem is that the Due is not able to output continuously at 40MHz, the 64+1+5 bit data is outputted as multiple bursts of 8 bits (1 byte) at a time. The clock and LE behave as expected.
Using it this way did not program the LM96570 as expected. It actually messed the other registers. For example, after a cold startup, the outputs are as expected (See figure 15). Now I use my Arduino Due to write 0x00 to register 0x00. I expect nothing to change. However, what I see now is that some of my other channels delay would change. (eg chan 4 and 5 would increase to 150ns, whereas the other ones are unchanged). Thus, I suspected the non continuous serial was to blame.
I then slowed down the SPI clock on the arduino to be able to obtain a continuous sCLK (That was achieved at 800kHz). However now, nothing would program at all. Again, I tried changing the delay of register 0x00 to 0x0000. Nothing changed. Great! However trying to program register 0x00 to a delay of 00 111 00000000001110 111 b 14CD + 7FD, similar to channel 7, nothing happened.
Thus, I am suspecting there is a minimum serial clock frequency required. If so, what is that minimum frequency? If not, what am I doing wrong??
Thanks,
Michael
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