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R2D1:
I supposed it to be some kind of detection for the bidirectional line being stuck in low/high state (but never investigated to it further!!! just a thought!): for example, if the ICD wants to pull it up via output RC4 (or RC5) and resistor, it would be able to detect stuck state reading...
@andy:
But in 4550, when it's updating itself, it is running some code (USB+reprogramming), so some kind of code area must be left untouched?
You mean 4550 (there I wanted to patch)? 877 firmware untouched, that's for sure!
Are there any 4550-flash-images available, before and after 7.31 to...
@slovak:
PIC18f2550 datasheet, page363 (Absolute Maximum Ratings), note 2 says: "Voltage spikes below VSS at the MCLR/VPP/RE3 pin, inducing currents greater than 80 mA, may cause
latch-up. Thus, a series resistor of 50-100Ω should be used when applying a “low” level to the MCLR/VPP/
RE3 pin...
Hi everybody!
I've become aware of your great project a few days ago by your link placed in the guestbook of my page. Congratulations to your efforts getting Microchip's ICD2_4550_BOOT work!!! :D
Of course I have to try and build this USB-Clone now that silly Cypress isn't needed anymore :-)...
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