Having made a mistake in my board design, I'd like to figure out whether I can (reasonably easily) get around it and make it work.
As indicated in the subject, I'm using the ADAU1701 with an external EEPROM for self-boot. The circuit is similar to the ADAU1701 mini evaluation board, so I will program the ADAU with a USBi from SigmaStudio.
The mistake I made is that I placed a chip that is driving the RESET line (without jumper or switch to selectively disconnect it). The RESET line (the one that goes to the ADAU1701, labeled AUDIO_RESET in the schematic, shown below) is being held at logical 0. The one that comes from the USBi (labeled AVR_RESET in the schematic), at this point has absolutely no effect --- it is connected to the RESET pin of an AVR microcontroller, with a 10k pullup.
SigmaStudio cannot connect to the board to download the compiled model, or save latest compilation to EEPROM. In either case, it "freezes" and when interrupted it reports it could not connect.
I am supplying power to the board (separately --- a 12V input goes to a 3.3V DC/DC switching regulator). Those 3.3V go to the ADAU1701 and to the EEPROM.
Below are the relevant sections of the schematic --- the connections to the USBi and the related ADAU1701 pins.
Question #1: should it work, with the ADAU1701 RESET line being held to 0 (active) ??Question #2: any suggestions to get around the problem?
Sorry for the problems. There are a few other details to take care of.
The Write Protect is being puled up. This is not a problem during normal operation but it is a problem when you are…
Let me take these questions a step at a time.
Have a look at this schematic of the Evaluation board:
Note that all the switch does is ground the WP pin of the EEPROM. The WP pin of the…