Board Support Package for the Stem Player SP-1 hardware (nRF52840 + CS42L42 + TAS2505 + BQ24232 + eMMC).
Fork this repo to build new firmware for the Stem Player hardware — synths, MIDI controllers, audio effects, or custom Stem Player variants.
# Configure (one-time)" /path/to/zephyr-venv/bin:$PATH " # Build# Flash
Directory
Contents
boards/Full board definition (DTS, pinctrl, defconfig)
drivers/audio/CS42L42 headphone codec + TAS2505 speaker amp drivers
drivers/charger/BQ24232 charger driver (GPIO-based)
include/SMF C++ facade, utility headers
subsys/system/Watchdog + reset breadcrumbs
subsys/power/Battery/charger/USB monitor
app/Minimal 2-state HSM skeleton
Device
Address
Function
CS42L42
0x48
Headphone DAC/ADC codec
TAS2505
0x18
Speaker amplifier
I2S0 (48kHz, 24-bit, master)
Signal
Pin
BCLK
P0.12
LRCK
P0.11
SDOUT
P1.09
Bluetooth UART (CYBT-353027-02)
Signal
Pin
TX
P1.02
RX
P1.04
RTS
P1.01
CTS
P1.03
Reset
P0.10
Channel
AIN
Pin
Function
0
AIN4
P0.28
Battery voltage (divider)
1
AIN3
P0.05
Fader 1
2
AIN6
P0.30
Fader 2
3
AIN2
P0.04
Fader 3
4
AIN7
P0.31
Fader 4
5
AIN0
P0.02
Track button ladder
6
AIN1
P0.03
Volume/transport ladder
PWM
Outputs
Function
PWM2
P0.29, P0.26, P1.15, P1.14
Track LEDs (1-4)
PWM3
P0.01, P1.12, P0.00, P1.13
Play LEDs (1-4)
Pin
Function
P0.27
Function button (active high)
P1.10
Button common rail (regulator)
P0.13
Oscillator enable
P0.14
eMMC VccQ enable
P1.08
eMMC reset
P0.09
TAS2505 reset
P0.15
CS42L42 reset
Pin
Function
P0.24
nPGOOD (power good, active low)
P0.22
nCHG (charging active, active low)
P0.21
CE (charge enable)
P0.19
ISET override
Add source files to APP_SOURCES in CMakeLists.txt
Extend AppMachine in AppStateMachine.hpp with your subsystem pointers
Add new states to the AppState enum and state table
Initialize your subsystems in main.cpp before app::run()
The HSM uses Zephyr's SMF (State Machine Framework) with a C++ facade in include/stem_player/Smf.hpp.
Bare BSP: ~168 KB FLASH (18%), ~43 KB RAM (17%). Full Stem Player firmware uses ~264 KB FLASH, ~219 KB RAM. You have plenty of room.