Electronics > Beginners
What does this circuit diagram say about triggering a reset?
sertyrion:
I am working with a ADUCM350 chip on the Spectra and trying to upload firmware to it.
I am able to connect to the device with a Segger JLINK with VCOM support. I'm able to read memory of the chip, however it fails at erasing the chip.
In looking up documentation about the Analog Devices ADUCM350, it says this about erasing the chip:
--- Quote ---The Monitor Status window will issue instructions to “Press Download and pulse Reset on hardware”. This implies keeping the SERIAL DOWNLOAD button (S6) on the motherboard depressed while pressing and releasing the RESET button (S5) before releasing the SERIAL DOWNLOAD button.
--- End quote ---
There doesn't seem to be any button the Spectra to do that, looked through documentation on PCB git.
However there is a diagram that talks about "RESET" and "DOWNLOAD" on page 4 of the pdf:
https://github.com/OpenEIT/EIT_EE/blob/master/Spectra.PDF
Attached is the relevant image. What is that circuit diagram saying about triggering a reset? I can provide images of device if needed.
https://www.crowdsupply.com/mindseye-biomedical/spectra
Ammar:
Without reading any of the links or resources you provided (which you should provide just in case, so thank you) you can tell from the circuit diagram that the reset is active low. The pull up resistor holds the reset pin high and connecting it to GND will reset the device. The capacitor is there to provide filtering/smoothing to stop any spurious signals getting into the reset pin and causing a false reset.
rstofer:
At startup, the capacitor will be discharged. When power is first applied, the capacitor holds the reset signal low for a short period of time while it charges. This is a very common approach to power-on reset.
We know that the time constant Tau=R*C is 1 ms and in that time the voltage on the capacitor will charge to 63% of Vcc. Without doing the math, it is likely that the signal will be below the logic '1' threshold for, perhaps, 500 us. Maybe a little less, maybe a little more, it depends on the threshold voltage.
R is in Ohms, C is in Farads so Tau = (1 * 104) * (1 * 10-7) = 1 * 10-3 = 1 ms
We also know the charging equation
Vout = Vin * (1-e-t/Tau) and it turns out that at t = 1 Tau the output is 63% of the input.
sertyrion:
Thanks for the responses.
I've tried grounding the reset pin on the SWD programming header, then pulse a reset, and that doesn't seem to make a difference.
Here is the pdf on how to initiate a serial download:
https://www.analog.com/media/en/technical-documentation/application-notes/AN-1262.pdf
I'll keep poking at it.
rstofer:
Are you sure you are supposed to use JTAG? The AN-XXXX document talks about 'serial' programming and the board apparently has the FTDI USB->Serial chip. Does the serial port show up in Device Manager?
Navigation
[0] Message Index
[#] Next page
Go to full version