(20230417) KLST_PANDA Prototyping

i will start the prototyping with ST’s development board NUCLEO-H723ZG. it allows to test most ( not all ) features and peripherals. PS { the boards connectors need to be equipped with double-row pin headers first … grrrmpf }

i am still struggling with one fundamental decision and that is whether i should produce smaller PCBs ( e.g for external memory BGA-24 IC ) and test them individually or if i should just take a leap of faith and design the entire board, planning 1–2 revision rounds. hmmm, difficult …

these are the sections or modules i want to test:

display

• dimming backlight (FAN5333) with PWM + 40-pin TFT Friend - FPC Breakout with LED Backlight Driver
  • see Controlling 3.5” TFT Through PWM
• capacitive touch interface (ADS7843)
• parallel LTDC interface ( is external memory required? )
• decide ( and order ) displays (13×) ( see research.KLST_PANDA–TFTs.md )

external memory

• BGA-24 memory (APS12808L-3OBM-BA)
• Octo-SPI/HyperRAM™ interface
• not sure how to test the BGA-24 memory IC? to just have this manufactured as a PCB seems a bit excessive

battery + power supply

• test charging circuit (TP5400)
• with Lolin D1 Mini Battery Shield
• test with battery type 18650
• can the circuit charge and supply power simultanously?
• do we need a hardware on/off-switch? or can this also be done in software?

USB-C

• are 2× USB-C connectors required or would a single one work?
• one for charging or power supply
• … and one for USB Device/Host where it could also power the board when connected as a ‌USB Device

audio codec

• test audio codec (WM8904)
• with PIC32 AUDIO CODEC DAUGHTER CARD (AC328904)

SDCard

• test 4-bit wide SDIO/SDMMC interface
• test card detect functionality

ADC+DAC

• test ADC
• test DAC

microphone

• test MEMS microphone ( via I2S )
• with Adafruit I2S MEMS Microphone Breakout - SPH0645LM4H

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@todo(elaborate on the details) @todo(see 2022-07-19-KLST_PANDA_starting_design_phase.md )

• MCU: STM32H723ZGT
• display
  • 4.3” 480×272
  • capacitive touch ( ADS7843 )
  • dimmable backlight ( PWM+FAN5333 )
  • LTDC interface ( parallel )
• rechargable battery
  • type 18650
  • with PCB mounted holder e.g MY-18650-01
  • recharging circuit?
  • see KLST_GRASS
• USB-C
  • 2×
  • one for charging
  • one for USB Device/Host devices
• audio codec
  • WM8904
• external memory
  • APS12808L-3OBM-BA
  • Octo-SPI/HyperRAM™ interface
• SDCard
  • 4-bit wide bus
  • with card detect
• microphone
  • MEMS microphone ( via I2S )
  • e.g GMA4030H11-F26
• DAC+ADC
  • DAC(1×)+ADC(3×)
  • connection to modular synth?!?
  • 12V tolerant ( or modular connection as extension board = 0.0—3.3V > -12.0–12.0V + -1.0–1.0V>-5.0>5.0V(?) )
• GPIO
  • what layout?
  • maybe case with fake shrouded connectors ( see IDC housing )
• LEDs
  • only 3 LEDs
• buttons
  • reset, boot, programmer
• mechanical keybord keys
  • 2×
  • just below encoders?
• programmer interface
  • STD14
  • pogo pin connector ( without housing on front-side )
• case+shape
  • switch?
  • portrait mode?
  • something unique!!!
  • hole for a strap
  • black&white PCB
• on/off switch(?) “just thought that when we have a battery on board there might be the need to be able to switch the power supply on or off”