64 lines
1.8 KiB
Plaintext
64 lines
1.8 KiB
Plaintext
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# pocket computer M4
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The PCM4 (pocket computer / M4) is a handheld computing device based
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around the Keyboard FeatherWing [1] and the Adafruit Feather M4 [2].
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The Feather M4 has 512K of flash memory, 192K of RAM, and 2M QSPI [3]
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flash.
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[1] https://www.tindie.com/products/arturo182/keyboard-featherwing-qwerty-keyboard-26-lcd/
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[2] https://learn.adafruit.com/adafruit-feather-m4-express-atsamd51?view=all
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[3] https://github.com/adafruit/Adafruit_QSPI
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It will have a scheme-based operating system.
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## Feather M4 pinouts
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+ A0: reserved
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+ A1: reserved
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+ A2: reserved for RFM9X CS
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+ A3: reserved for RFM9X RST
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+ A4: reserved for airlift ESPBUSY
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+ A5: reserved for airlift ESPRESET
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+ D4: reserved for RFM9X IRQ
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+ D5: SD card CS
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+ D6: STMPE CS
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+ D9: LCD CS
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+ D10: LCD DC
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+ D11: neopixel
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## Peripherals
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+ Display: 320x240 touchscreen
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+ ILI9341 LCD controller
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+ STMPE610 touchscreen
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+ Keyboard: BB Q10 keyboard + 4x tactile buttons + 5-way switch
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+ I2C address: 0x1F
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+ Planned: DS3231 RTC
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+ I2C address: 0x66
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+ Planned: RFM95 LoRa featherwing
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+ Planned: ESP32 airlift
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+ Planned: ATECC608A cryptoprocessor
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## Boot sequence
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1. Stage 1: UF2 bootloader [4][5]
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2. Stage 2: base hardware environment
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+ hardware init
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+ I2C/SPI interface
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+ SD card
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+ RTC core
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+ scheme core
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3. Load boot.scm from SD card.
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Stretch goal:
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+ Holding down the center button in the joystick should bring up a menu
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of scheme files on the SD card, allowing the user to select the boot
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code.
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Note that each stage is as minimal as possible, so stage 2 should
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contain just enough to load the operating system from boot.scm,
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which should contain the actual operating system.
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[4] https://learn.adafruit.com/adafruit-feather-m0-express-designed-for-circuit-python-circuitpython/uf2-bootloader-details
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[5] https://github.com/Microsoft/uf2
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