Second 3.3V generation for the bus

fachat commented 1 month ago

Currently the bus uses the same 3.3V that is used for the main FPGA, CPU, RAM etc.

At least the bus, if not even the net and SDcard ports should have their own 3.3V generation.

fachat commented 1 month ago

Currently the old SDcard connector uses 5V, not 3.3V

USB MAX3421 max rating is 55mA at 3.3V
ENC28J60 while transmitting: 180mA at 3.3V
SDCards Class 10 specifiy up to 100mA at init, 200mA in high speed mode, and 500mA in "other functions" (https://www.farnell.com/datasheets/1683445.pdf)
ESP32-C3-WROOM-02: up to 345mA peak (https://www.espressif.com/sites/default/files/documentation/esp32-c3-wroom-02_datasheet_en.pdf)
Spartan6 quiescent mode approx. 8mA, 40mA during fuse. Lots if pins are added. Up to multiple Amps possible. Currently during full speed operation, FPGA stays quite cool actually, so in reality not that much
IS61C512 (2x) up to 70mA (RAM)

fachat commented 1 month ago

I think I should have a 2nd 3.3V generator for SDcard, Network (Eth or Wifi/ESP32), and bus (for the ultipet)

fachat commented 1 month ago

Added in branch 1.2a

fachat / cbm_ultipet