Difference between revisions of "84PCE:Ports:000D"
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Latest revision as of 22:23, 20 February 2021
Synopsis
Port Number: 000D
Function: Power control
Details
This port enables power to various parts of the ASIC. Each region reads as 0 when unpowered.
Bit [0]
USB controller power. Resets when unpowered. Returning to the OS without reinitializing causes it to freeze while USB is connected.
Bit [1]
LCD controller power. Resets when unpowered. The LCD does not update until the controller is initialized properly.
Bit [2]
Power for RAM range D20000-D3FFFF. When unpowered, its content is quickly randomized.
Bit [3]
Power for VRAM range D40000-D7FFFF. When unpowered, its content is quickly randomized.
Bits [4:7]
Writes have no effect. These bits read as 1 if the subsystems controlled by the corresponding bits in 0-3 are receiving power. There is a slight delay between changing bits 0-3 & these changing in response.