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raspberrypi / usbboot

Raspberry Pi USB booting code, moved from tools repository
Apache License 2.0
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nRPIBOOT for CM4 #67

Closed trejan closed 3 years ago

trejan commented 3 years ago

CM4 datasheet calls it nRPIBOOT and doesn't mention the GPIO number.

cleverca22 commented 3 years ago

something else i worry about, but its probably just in the missing half of the schematic

gpio40 is the MISO line on an rpi4b, so pulling that to gnd would cause all replies from the eeprom to be silenced, but it could potentially also damage the output driver on the eeprom my guess as to the solution, is to just have a resistor on that eeprom to limit the current being sunk into gnd, but without schematics its hard to confirm

knowing which way its been done, may also help solve issues where rpi4b units cant be reflashed due to damaged uSD sockets