GuitarProjectGuy
New member
Hi Everyone, I am new to this forum and I appreciate in advance any support you can provide.
I have a T4.1 and I have not been able to get the ADC to work. I am using the recommended input circuit, which measures fine (my input is a guitar pickup which, for the guitars I play, outputs between 0 and ~200mV. The signal is good from both the guitar and as measured on the suggested circuit (note I changed the 10k resister to 2.2k. as per the guidance on that site). After failing to measure the signal with several of the programs on the GitHub pedvide/ADC site (the peak detector and the mono pass through to a working test amp I have) I ran the hardware test. It wrote the following:
PULLUP TEST PASS
PULLDOWN TEST PASS
COMPARE TEST PASS
COMPARE RANGE TEST PASS
AVERAGE TEST PASS
But then all of the sample tests at various resolutions failed, and the output writes PULLUP FAILED after the sample speed details.
I apologize in advance for not pasting the complete output, I didn't save but can run again tomorrow if that would be helpful.
The input pin I have been using is A2 (pin 16). I can also build a regulated external power source as a reference, but again, I would like to see the internal reference work and learn why it doesn't seem to be working for me.
Note that I have never used an external power source and I have never fed the ADC an input greater than the one described above. I have a couple of arduinos and they work fine with the same input current for the purposes of ADC sampling (note I can certainly run the signal through a pre-amp before sending to the ADC for test purposes, but I would prefer not to due to the work I am doing, and I don't see any reason why the ADC on the NXP chip would not accept instrument level input like this). I plan to buy an external shield to minimize noise, etc. but they are not currently available and I would like to understand the chip ADC's before I do this.
Please know that I am a musician with a strong audio engineering background but aside from the arduino, I am quite new to working with microcontrollers. I admittedly may be doing something wrong (real newbie kinda wrong) but it would be good to understand why the HW test read as it did and I would greatly appreciate any other suggestions anyone has for me. Thank you in advance for your patience with all this.
Finally, one side question, is the purpose of the suggested ADC input circuit to provide an optimized impedance for the chip? I tried to read the data sheet to learn the expected impendence perimeters, but I couldn't find that specifically.
Thank you!
I have a T4.1 and I have not been able to get the ADC to work. I am using the recommended input circuit, which measures fine (my input is a guitar pickup which, for the guitars I play, outputs between 0 and ~200mV. The signal is good from both the guitar and as measured on the suggested circuit (note I changed the 10k resister to 2.2k. as per the guidance on that site). After failing to measure the signal with several of the programs on the GitHub pedvide/ADC site (the peak detector and the mono pass through to a working test amp I have) I ran the hardware test. It wrote the following:
PULLUP TEST PASS
PULLDOWN TEST PASS
COMPARE TEST PASS
COMPARE RANGE TEST PASS
AVERAGE TEST PASS
But then all of the sample tests at various resolutions failed, and the output writes PULLUP FAILED after the sample speed details.
I apologize in advance for not pasting the complete output, I didn't save but can run again tomorrow if that would be helpful.
The input pin I have been using is A2 (pin 16). I can also build a regulated external power source as a reference, but again, I would like to see the internal reference work and learn why it doesn't seem to be working for me.
Note that I have never used an external power source and I have never fed the ADC an input greater than the one described above. I have a couple of arduinos and they work fine with the same input current for the purposes of ADC sampling (note I can certainly run the signal through a pre-amp before sending to the ADC for test purposes, but I would prefer not to due to the work I am doing, and I don't see any reason why the ADC on the NXP chip would not accept instrument level input like this). I plan to buy an external shield to minimize noise, etc. but they are not currently available and I would like to understand the chip ADC's before I do this.
Please know that I am a musician with a strong audio engineering background but aside from the arduino, I am quite new to working with microcontrollers. I admittedly may be doing something wrong (real newbie kinda wrong) but it would be good to understand why the HW test read as it did and I would greatly appreciate any other suggestions anyone has for me. Thank you in advance for your patience with all this.
Finally, one side question, is the purpose of the suggested ADC input circuit to provide an optimized impedance for the chip? I tried to read the data sheet to learn the expected impendence perimeters, but I couldn't find that specifically.
Thank you!