??? 09/16/12 23:22 Read: times |
#188361 - TIA and ADC clock speed. Responding to: ???'s previous message |
Richard and Kai, thanks for the thoughts.
Yes, I realize the conversion clock must be slower. I used every combination with the clock speed bits. Clock is currently at the default 2mhz. The processor is running at 20mhz. The TIA- also yes. Transimpedence amp AKA current to voltage converter. I have an LM324 connected as a TIA. The LM324 operates at 3.3V, unlike the TL084 which needs over twice that. I am assuming the LM324 will work in this circuit but don't know for sure. A lot of internet TIA examples use the 324. My circuit AT89LP6440 with 3.3V supply. One led connects to P1.0 for visual. dac connections: neg to neg, pos to pos (Dac to 324 opamp) positive connections go to a pot(3.3V to ground) so I can vary that level and easily set it to Vdd/2. Output follows the pot + input. Feedback resistor- 4.7K to 100K. software simply increments A, sends it to the msb Dac register(DADH), then a slight delay of $FF clock cycles. The DAC and ADCE bits are set, as instructed. I set the go bit (DADC.6) for each conversion with ORL DADC.6. I have gone over and over Atmels 6440 pdf file, setting the bits as instructed, trying different combinations. Can't see it yet. Still no output. Rick |
Topic | Author | Date |
AT89LP6440 no dac output | 01/01/70 00:00 | |
You're aware that this is a differential DAC, right? | 01/01/70 00:00 | |
TIA and ADC clock speed. | 01/01/70 00:00 | |
Have you noticed... | 01/01/70 00:00 |