PicoBoy

The PicoBoy is a powerful mini handheld measuring just 3×5 ㎝. It is suitable for learning programming, developing your own games or simply playing with it. All you need is a PC, the PicoBoy and a USB-C cable. As the PicoBoy based on the RP2040 SoC [33] by Raspberry Pi Ltd. and is compatible with the Raspberry Pi Pico programming model and process, there are countless other tutorials, examples and libraries on the internet to make programming easier.

Board Overview

Hardware

The PicoBoy [15] is a special mini sized RP2040 development board.

Features and Resources

Printed Circuit Board

5V/125~250㎃ 3.0~3.3V/180~200㎃

133㎒ 2㎆ 264㎅ USB-C CR2032 UF2

RST BOOT UP|DOWN|LEFT|RIGHT|ENTER

RED YELLOW GREEN OLED PASSIVE 3-DOF

9 4 4 1 1

  • Dual core Arm Cortex-M0+ processor running up to 133㎒

  • 264㎅ on-chip SRAM

  • 2㎆ on-board QSPI flash with XIP capabilities

  • USB 1.1 controller (host/device)

  • On-board USB-C connector

  • On-board 3.3V DC-DC buck-boost converter with 600㎃ switch

  • On-board CR2032 coin battery holder

  • On-board RESET button

  • On-board BOOT button

  • On-board 1 User joystick (5 keys)

  • On-board 3 User LEDs

  • On-board 1 passive magnetic speaker

  • On-board 3-DOF IMU sensor

  • On-board 1.3-inch 128×64 pixels OLED, monochrome white (serial)

  • 1 RST signal to OLED controller

  • 1 C/D signal to OLED controller

  • 1 I2C controller for acceleration sensor

  • 1 SPI controller for OLED

  • 4 PWM channels for LEDs and speaker

  • 4 ADC analog inputs

  • 8 Programmable I/O (PIO) state machines for custom peripherals

  • 1 Watchdog timer peripheral

  • 1 Temperature sensor on-chip

Design Data

 PicoBoy

Positions

PicoBoy details

Front side:

  1. SH1106
    1.3-inch 128×64 pixels monochrome white OLED
  2. User joystick
    UP, DOWN, LEFT, RIGHT, ENTER
  3. W25Q16JV
    2㎆ NOR-Flash
  4. LED monochrome
    user LEDs for diagnostic (not power indicator)

Back side:

  1. RP2040

  2. USB Type-C connector
    Supports USB1.1 hosts and slave devices

  1. Power Supply Switch

  2. RESET and BOOT button
    press it when resetting to enter download mode
  3. Magnetic Speaker
    3.0Vo-p (2.0~4.0V) @ 4,000㎐ with ≫73㏈A
  4. STK8BA58
    3-axis MEMS acceleration sensor
  5. CR2032
    3.0V @ 235㎃h coin battery holder
  • XC6206P332MR (662K)
    200㎃ low dropout, low quiescent current
    3.3V power supply, SOT-23
  • S8050 (J3Y)
    SMD NPN Transistor 300㎽, 40V @ 500㎃, SOT-23

Data Sheets

Flash partitions

QSPI NOR-Flash

bootrom

code_partition

storage_partition

primary 2㎆

256B

1㎆ - 256B

1㎆

Pinouts

The peripherals of the RP2040 SoC [33] can be routed to various pins on the board. The configuration of these routes can be modified through DTS. Please refer to the datasheet to see the possible routings for each peripheral. The default assignments for the on-board wiring is defined below.

Pin Mapping
on-board:

9 4 4 1 1

on-board:

1 RST 1 BOOT 1 CURSOR 1 RED 1 YELLOW 1 GREEN 1 OLED 1 PASSIVE 3-DOF

Default Zephyr On-Board Mapping

 

Buttons

  • ENTER : GP0 (PWM0)
  • UP : GP1 (PWM1)
  • RIGHT : GP2 (PWM2)
  • DOWN : GP3 (PWM3)
  • LEFT : GP4 (PWM4)

LEDs

  • RED : GP5 PWM5
  • YELLOW : GP6 PWM6
  • GREEN : GP7 PWM7

Display and Speaker

  • OLED : GP8 (PWM8)
    on-board OLED data/cmd OLED_DC
  • OLED : GP9 (PWM9)
    on-board OLED reset OLED_RST
  • OLED : GP10 (PWM10)
    on-board OLED chip select OLED_CS
  • n.c. : GP11 (PWM11)
  • n.c. : GP12 (PWM12)
  • n.c. : GP13 (PWM13)
  • n.c. : GP14 (PWM14)
  • PASSIVE : GP15 PWM15
  • n.c. SPI0_RX : GP16 (PWM0)
  • n.c. SPI0_CSN : GP17 (PWM1)
  • OLED SPI0_SCK : GP18 (PWM2)
    on-board OLED i/f clock OLED_CLK
  • OLED SPI0_TX : GP19 (PWM3)
    on-board OLED i/f data OLED_DIN

Sensor I/O

  • I2C0_SDA : GP20 (PWM4)
    on-board acc. sensor i/f data ACCS_SDA
  • I2C0_SCL : GP21 (PWM5)
    on-board acc. sensor i/f clock ACCS_SCL

GPIO and ADC

  • n.c. : GP22 (PWM6)
  • n.c. : GP23 (PWM7)
  • n.c. : GP24 (PWM8)
  • n.c. : GP25 (PWM9)
  • n.c. ADC_CH0 : GP26 (PWM10)
  • n.c. ADC_CH1 : GP27 (PWM11)
  • n.c. ADC_CH2 : GP28 (PWM12)
  • n.c. ADC_CH3 : GP29 (PWM13)

Supported Features

Similar to the Raspberry Pi Pico the board configuration supports the following hardware features:

Hardware Features Supported by Zephyr

Peripheral

Kconfig option

Devicetree compatible

Zephyr API

PINCTRL

CONFIG_PINCTRL

raspberrypi,pico-pinctrl

Pin Control API

GPIO

CONFIG_GPIO

raspberrypi,pico-gpio

General-Purpose Input/Output (GPIO)

UART

CONFIG_SERIAL
raspberrypi,pico-uart
arm,pl011

Universal Asynchronous Receiver-Transmitter (UART)

UDC (USB Device Controller)

CONFIG_USB_DEVICE_STACK_NEXT

raspberrypi,pico-usbd

USB device support APIs

I2C

CONFIG_I2C

raspberrypi,pico-i2c

Inter-Integrated Circuit (I2C) Bus

SPI

CONFIG_SPI
raspberrypi,pico-spi
arm,pl022

Serial Peripheral Interface (SPI) Bus

PWM

CONFIG_PWM

raspberrypi,pico-pwm

Pulse Width Modulation (PWM)

ADC

CONFIG_ADC

raspberrypi,pico-adc

Analog-to-Digital Converter (ADC)

Temperature (Sensor)

CONFIG_SENSOR

raspberrypi,pico-temp

Sensors

RTC

CONFIG_RTC

raspberrypi,pico-rtc

Real-Time Clock (RTC)

Timer (Counter)

CONFIG_COUNTER

raspberrypi,pico-timer

Counter

Watchdog Timer (WDT)

CONFIG_WATCHDOG

raspberrypi,pico-watchdog

Watchdog

Flash

CONFIG_FLASH

raspberrypi,pico-flash-controller

Flash and Flash map

PIO

CONFIG_PIO_RPI_PICO

raspberrypi,pico-pio

N/A

UART (PIO)

CONFIG_SERIAL

raspberrypi,pico-uart-pio

Universal Asynchronous Receiver-Transmitter (UART)

SPI (PIO)

CONFIG_SPI

raspberrypi,pico-spi-pio

Serial Peripheral Interface (SPI) Bus

WS2812 (PIO)

CONFIG_LED_STRIP

worldsemi,ws2812-rpi-pico-pio

N/A

DMA

CONFIG_DMA

raspberrypi,pico-dma

Direct Memory Access (DMA)

HWINFO

CONFIG_HWINFO

N/A

Hardware Information

VREG

CONFIG_REGULATOR

raspberrypi,core-supply-regulator

Regulators

RESET

CONFIG_RESET

raspberrypi,pico-reset

Reset Controller

CLOCK

CONFIG_CLOCK_CONTROL
raspberrypi,pico-clock-controller
raspberrypi,pico-clock

Clock Control

NVIC

N/A

arm,v6m-nvic

Nested Vector Interrupts Controller

SYSTICK

N/A

arm,armv6m-systick

Other hardware features are not currently supported by Zephyr. The default configuration can be found in the following Kconfig file:

Board Configurations

The board can be configured only for the following single use cases.

west build -b picoboy/rp2040

Use the native USB device port with CDC-ACM as Zephyr console and for the shell.

Connections and IOs

The PicoBoy [16] website has detailed information about board connections. Download the different datasheets there or as linked above on the positions for more details.

System Clock

The RP2040 [33] MCU is configured to use the 12㎒ external crystal with the on-chip PLL generating the 125㎒ system clock.

GPIO (PWM) Ports

The RP2040 [33] MCU has 1 GPIO cell which covers all I/O pads and 8 PWM function unit each with 2 channels beside a dedicated Timer unit. Only 4 PWM channels are available, for the three user LEDs and the passive magnetic speaker.

ADC/TS Ports

The RP2040 [33] MCU has 1 ADC with 4 channels and an additional fifth channel for the on-chip temperature sensor (TS). The ADC channels 0-3 are not available for any on-board function.

The external voltage reference ADC_VREF is directly connected to the 3.3V power supply.

SPI Port

The RP2040 [33] MCU has 2 SPIs. The serial bus SPI0 is connect to the on-board OLED display over GP19 (MOSI), GP16 (MISO), GP18 (SCK), and GP17 (CSn), but only MOSI and SCK is used for write-only communication. The display chip-select signal will driven as simple GPIO by GP10 and the display itself does not provide any data out signal (MISO).

SPI1 is not available in any default setup.

I2C Port

The RP2040 [33] MCU has 2 I2Cs. The serial bus I2C0 is connect to the on-board acceleration sensor over GP20 (I2C0_SDA), GP21 (I2C0_SCL). I2C1 is not available in any default setup.

Serial Port

The RP2040 [33] MCU has 2 UARTs. Neither UART0 nor UART1 are available in any of the default setups. When ever a Zephyr serial console will be needed, the USB port have to be used.

USB Device Port

The RP2040 [33] MCU has a (native) USB device port that can be used to communicate with a host PC. See the USB sample applications for more, such as the USB CDC ACM UART sample sample which sets up a virtual serial port that echos characters back to the host PC. The board provide the Zephyr console per default on the USB port as CDC ACM:

USB device idVendor=2e8a, idProduct=000a, bcdDevice= 4.04
USB device strings: Mfr=1, Product=2, SerialNumber=3
Product: PicoBoy (CDC ACM)
Manufacturer: JSED (Raspberry Pi)
SerialNumber: BD774B2618DAAA7D

Programmable I/O (PIO)

The RP2040 SoC [33] comes with two PIO periherals. These are simple co-processors that are designed for I/O operations. The PIOs run a custom instruction set, generated from a custom assembly language. PIO programs are assembled using pioasm, a tool provided by Raspberry Pi. Further information can be found in the Raspberry Pi Pico C/C++ SDK [10] document, section with title “Using PIOASM, the PIO Assembler”.

Zephyr does not (currently) assemble PIO programs. Rather, they should be manually assembled and embedded in source code. An example of how this is done can be found at drivers/serial/uart_rpi_pico_pio.c or drivers/spi/spi_rpi_pico_pio.c.

Programming and Debugging

Flashing

The board can only be flashed with a UF2 file. There is no SWD connector.

Using UF2

By default, building an application for the board will generate a build/zephyr/zephyr.uf2 file. If the board is powered on with the BOOTSEL button pressed, it will appear on the host as a mass storage device:

USB device idVendor=2e8a, idProduct=0003, bcdDevice= 1.00
USB device strings: Mfr=1, Product=2, SerialNumber=0
Product: RP2 Boot
Manufacturer: Raspberry Pi
SerialNumber: E0C9125B0D9B

The UF2 file should be drag-and-dropped or copied on command line to the device, which will then flash the board.

RP2040 Boot-ROM

Each RP2040 SoC [33] ships the UF2 compatible [6] bootloader pico-bootrom-rp2040 [12], a native support in silicon. The full source for the RP2040 bootrom at pico-bootrom-rp2040 [12] includes versions B0, B1 and B2 of the bootrom, which correspond to the same silicon revisions, respectively.

Note that every time you build a program for the RP2040, the Pico SDK selects an appropriate second stage bootloader based on what kind of external QSPI Flash type the board configuration you are building for was giving. There are several versions of boot2 [11] for different flash chips, and each one is exactly 256 bytes of code which is put right at the start of the eventual program binary. On Zephyr the boot2 versions are part of the Raspberry Pi Pico HAL [14] module. Possible selections:

CONFIG_RP2_FLASH_AT25SF128A:

boot2_at25sf128a.S [36]

CONFIG_RP2_FLASH_GENERIC_03H:

boot2_generic_03h.S [37]

CONFIG_RP2_FLASH_IS25LP080:

boot2_is25lp080.S [38]

CONFIG_RP2_FLASH_W25Q080:

boot2_w25q080.S [39]

CONFIG_RP2_FLASH_W25X10CL:

boot2_w25x10cl.S [40]

The board set this option to CONFIG_RP2_FLASH_W25Q080.

Further information can be found in the RP2040 Datasheet [34], sections with title “Bootrom” and “Processor Controlled Boot Sequence” or Brian Starkey’s Blog article Pico serial bootloader [13]

Debugging

The board does not provide any SWD connector, thus debugging software is not possible.

Basic Samples

LED Blinky and Fade

Red User LED Blinky by GPIO

See also Zephyr sample: Blinky.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/basic/blinky
west flash -d build/picoboy

Red User LED Blinky by PWM

See also Zephyr sample: PWM Blinky.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/basic/blinky_pwm
west flash -d build/picoboy

All User LED Fade by PWM

See also Zephyr sample: Fade LED.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/basic/fade_led
west flash -d build/picoboy

Red User LED On/Off by GPIO Button (Joystick ENTER)

See also Zephyr sample: Button.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/basic/button
west flash -d build/picoboy

Hello Shell on USB-CDC/ACM Console

Hello Shell

See also Bridle sample: Hello Shell.

west build -b picoboy/rp2040 -p -d build/picoboy bridle/samples/helloshell
west flash -d build/picoboy

Simple test execution on target

(text in bold is a command input)

uart:~$ hello -h
hello - say hello
uart:~$ hello
Hello from shell.
uart:~$ hwinfo devid
Length: 8
ID: 0xbd774b2618daaa7d

uart:~$ kernel version
Zephyr version 4.4.99

uart:~$ bridle version
Bridle version 4.4.99

uart:~$ bridle version long
Bridle version 4.4.99.0

uart:~$ bridle info
Zephyr: 4.4.99
Bridle: 4.4.99
uart:~$ device list
devices:
- clock-controller@40008000 (READY)
  DT node labels: clocks
- reset-controller@4000c000 (READY)
  DT node labels: reset
- cdc_acm_console_uart (READY)
  DT node labels: cdc_acm_console_uart
- timer@40054000 (READY)
  DT node labels: timer
- watchdog@40058000 (READY)
  DT node labels: wdt0
- dma@50000000 (READY)
  DT node labels: dma
- gpio-port@0 (READY)
  DT node labels: gpio0
- usbd@50110000 (READY)
  DT node labels: usbd zephyr_udc0
- adc@4004c000 (READY)
  DT node labels: adc
- flash-controller@18000000 (READY)
  DT node labels: ssi
- i2c@40044000 (READY)
  DT node labels: i2c0
- pwm@40050000 (READY)
  DT node labels: pwm
- vreg@40064000 (READY)
  DT node labels: vreg
- rtc@4005c000 (READY)
  DT node labels: rtc
- pwm-leds (READY)
  DT node labels: pwm_leds
- dietemp (READY)
  DT node labels: die_temp
- stk8ba58@18 (READY)
  DT node labels: stk8ba58
uart:~$ history
[  0] history
[  1] device list
[  2] bridle info
[  3] bridle version long
[  4] bridle version
[  5] kernel version
[  6] hwinfo devid
[  7] hello
[  8] hello -h

More Samples

3-Axis accelerometer data on USB-CDC/ACM Console

The samples are prepared for the on-board 3-DOF accelerometer connected to the I2C0 bus.

Chip-specific

Get 3-axis accelerometer data from an STK8BA58 sensor (polling mode only) using the Sensors API. See also Bridle sample STK8BA58 3-Axis Accelerometer Sample and also the console output in section Building on picoboy of the Bridle sample documentation.

Polling Mode

Get 3-axis accelerometer data from the on-board sensor (polling mode) using the Sensors API. See also Zephyr sample Generic 3-Axis accelerometer polling.

Invoke west build and west flash:

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/sensor/accel_polling
west flash -d build/picoboy

Simple test execution on target

*** Booting Zephyr OS build v4.4.99…***
     stk8ba58@18 [m/s^2]:    (    4.747595,    -1.710672,    -9.572076)
     stk8ba58@18 [m/s^2]:    (    4.747595,    -1.710672,    -9.572076)
     stk8ba58@18 [m/s^2]:    (    4.622658,    -1.710672,    -9.581686)
     stk8ba58@18 [m/s^2]:    (    4.718764,    -1.595345,    -9.610518)
     stk8ba58@18 [m/s^2]:    (    4.718764,    -1.595345,    -9.610518)

Trigger Mode

Get 3-axis accelerometer data from the on-board sensor (trigger mode) using the Sensors API. See also Zephyr sample Accelerometer trigger.

Hint

There is no interrupt line to the on-board 3-Axis accelerometer. This sample is not applicable.

Sounds from the speaker on USB-CDC/ACM Console

The sample is prepared for the on-board PWM_SPEAKER connected to the PWM channel at GP15 / PWM15 (PWM7CHB).

The PWM period is 880 ㎐, twice the concert pitch frequency of 440 ㎐.

PicoBoy Speaker Test

Speaker Test

Invoke west build and west flash:

west build -b picoboy/rp2040 -p -d build/picoboy bridle/samples/buzzer
west flash -d build/picoboy

Simple test execution on target

  1. play a beep

  2. play a folk song

  3. play a chrismas song

uart:~$ buzzer beep
uart:~$ buzzer play folksong
uart:~$ buzzer play xmastime

Input dump on USB-CDC/ACM Console

Print the input events related to the five on-board joystick keys using the Input subsystem API. That are:

UP : zephyr,code = <INPUT_KEY_UP>;
DOWN : zephyr,code = <INPUT_KEY_DOWN>;
LEFT : zephyr,code = <INPUT_KEY_LEFT>;
RIGHT : zephyr,code = <INPUT_KEY_RIGHT>;
ENTER : zephyr,code = <INPUT_KEY_ENTER>;

See also Zephyr sample: Input dump.

Joystick Test

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/subsys/input/input_dump
west flash -d build/picoboy

Simple logging output on target

*** Booting Zephyr OS build v4.4.99…***
Input sample started
I: input event: dev=gpio-keys        SYN type= 1 code=103 value=1
I: input event: dev=gpio-keys        SYN type= 1 code=103 value=0
I: input event: dev=gpio-keys        SYN type= 1 code=108 value=1
I: input event: dev=gpio-keys        SYN type= 1 code=108 value=0
I: input event: dev=gpio-keys        SYN type= 1 code=105 value=1
I: input event: dev=gpio-keys        SYN type= 1 code=105 value=0
I: input event: dev=gpio-keys        SYN type= 1 code=106 value=1
I: input event: dev=gpio-keys        SYN type= 1 code=106 value=0
I: input event: dev=gpio-keys        SYN type= 1 code= 28 value=1
I: input event: dev=gpio-keys        SYN type= 1 code= 28 value=0

Display Test and Demonstration

The following samples work with the chosen display. That is:

OLED : chosen { zephyr,display = &oled_panel; };
SH1106 : oled_panel: &sh1106_128x64 {};

Devicetree compatible

  • zephyr,lvgl-keypad-input with devicetree relation lvgl_keypad: lvgl-keypad { input = <&gpio_keys>; };

    UP : input-codes = <INPUT_KEY_UP>; : lvgl-codes = <LV_KEY_UP>;
    DOWN : input-codes = <INPUT_KEY_DOWN>; : lvgl-codes = <LV_KEY_DOWN>;
    LEFT : input-codes = <INPUT_KEY_LEFT>; : lvgl-codes = <LV_KEY_LEFT>;
    RIGHT : input-codes = <INPUT_KEY_RIGHT>; : lvgl-codes = <LV_KEY_RIGHT>;
    ENTER : input-codes = <INPUT_KEY_ENTER>; : lvgl-codes = <LV_KEY_ENTER>;

LCD Orientation and Bit Order Test

PicoBoy Display Test

Draw some basic rectangles onto the display using the Display driver API. See also Zephyr sample: Display.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/drivers/display
west flash -d build/picoboy

LVGL Basic Sample

Displays “Hello World!” in the center of the screen and a counter at the bottom which increments every second using the LVGL module on top of the Display driver API. See also Zephyr sample: LVGL basic sample.

west build -b picoboy/rp2040 -p -d build/picoboy zephyr/samples/subsys/display/lvgl
west flash -d build/picoboy

This sample comes with a Shell command line access to the LVGL backend on the console, here configured for a USB console:

Simple test execution on target

uart:~$ lvgl
lvgl - LVGL shell commands
Subcommands:
  stats   : Show LVGL statistics
  monkey  : LVGL monkey testing

uart:~$ lvgl stats
stats - Show LVGL statistics
Subcommands:
  memory  : Show LVGL memory statistics
            Usage: memory [-c]
                   -c  dump chunk information

uart:~$ lvgl stats memory
Heap at 0x20001618 contains 2047 units in 11 buckets

  bucket#    min units        total      largest      largest
             threshold       chunks      (units)      (bytes)
  -----------------------------------------------------------
        0            1            1            1            8
        1            2            2            2           16
        2            4            1            4           32
       10         1024            1         1326        10608

10660 free bytes, 5372 allocated bytes, overhead = 348 bytes (2.1%)
uart:~$ device list
devices:
- clock-controller@40008000 (READY)
  DT node labels: clocks
- reset-controller@4000c000 (READY)
  DT node labels: reset
- cdc_acm_console_uart (READY)
  DT node labels: cdc_acm_console_uart
- timer@40054000 (READY)
  DT node labels: timer
- watchdog@40058000 (READY)
  DT node labels: wdt0
- dma@50000000 (READY)
  DT node labels: dma
- gpio-port@0 (READY)
  DT node labels: gpio0
- usbd@50110000 (READY)
  DT node labels: usbd zephyr_udc0
- pwm@40050000 (READY)
  DT node labels: pwm
- vreg@40064000 (READY)
  DT node labels: vreg
- spi@4003c000 (READY)
  DT node labels: spi0
- sh1106-128x64@0 (READY)
  DT node labels: sh1106_128x64 oled_panel
- gpio-keys (READY)
  DT node labels: gpio_keys
- lvgl-keypad (READY)
  DT node labels: lvgl_keypad

References