Content originally posted in LPCWare by allankliu on Sat Dec 14 02:49:27 MST 2013
I have a mini board for LPC812M101JD20 (SO20, but not FD20). The attached PDF is its schematics. In this schematics, CP2102 was used as USB/UART bridge, two buttons (ISP/RST) are used to enter ISP mode to download the hex code via Flash magic software.
Currently I haven't populate onboard CP2102, but using an external PL2303. And I didn't populate 12MHz crystal as well, since I think IRC will be used during ISP anyway.
By pressing and releasing RST while holding ISP key, I can enter ISP mode and program hex code. However I can not enter ISP mode later with same actions.
Do I miss anything to enter ISP mode again?
Looking for quick suggestions, since I have already put them on production plan. I am going to use it as a mini-dev-kit for Android USB host application.