I have a deeply embedded application where frequent FW updates are a requirement. I will have access to toggle the boot-mode(BM) and reset(RST) pins to tell the MCU to enter the serial download state. So, I plan to send a command downstream to the 7026 which will trigger some sort of external circuitry to toggle the BM and RST pins. I have several options and please refer to the attached schematic:
Option 1. Use a supervisory IC such as the ADM708 where on receipt of the software download code, we trigger the BM and RST pins. Will this work? If so, how to improve it? This is option 1.
Option 2. Use FETs to simulate toggle switches to 3.3V and ground. My concern here is whether the i/ps to the FETs will hold to their previous set values once the reset pulse (/RESET) is applied to the 7026. I''m afraid of prematurely aborting the 'get-into-serial-download-mode' process. Any ideas here as well?
Which option should I choose?
Your help is greatly appreciated as time is not my friend. Need to get thsi working by weeks end.
Option 3 ...a paper by Jason Jiao and Raven Xue was written that supposedly highlights in application programming but our firmware folks don't trust it since Jason and Raven have never (to the best of our knowledge) proved that it works in real-life, so they are hesitant to put in the man-hours to prove it. It seems Jason and Raven left ADI.