The flashcart uses (rev4) or emulates (rev5+) a 2003 mapper. Most of its functionality (banking, flash access via SRAM) is provided.
AVR wake/sleep is controlled using 2003 GPIO bit 3.
To wake up the AVR:
One should wait around 12 ms (maybe less?) after sending this signal to ensure the AVR is awake.
To put the AVR to sleep:
The flashcart uses invalid RTC date/time values to provide custom commands. For this to work, the AVR must be awake (see above).
Format: RTC command 0x14 with parameters [0xA1, slot, 0, 0, 0, 0, 0, 0]
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Description: Configure the visible slot, from 0 to 15.