(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:

MCU

• STM32H723ZGT

display

• 4.3” 480×272
• capacitive touch interface (ADS7843)
• LTDC interface ( parallel )
• dimming backlight (FAN5333) with PWM + 40-pin TFT Friend - FPC Breakout with LED Backlight Driver
  • see Controlling 3.5” TFT Through PWM
• 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?
• with PCB mounted holder e.g MY-18650-01

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”

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

• 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(?) )

microphone

• test MEMS microphone ( via I2S )
• with Adafruit I2S MEMS Microphone Breakout - SPH0645LM4H
• e.g GMA4030H11-F26

GPIO

• what layout?
• maybe case with fake shrouded connectors ( see IDC housing )
• only 2 LEDs ( with PWM )

buttons

• reset, boot, programmer

mechanical keyboard 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