WeAct BluePill+

The WeAct Blue Pill Plus board is available in different versions, each with a specific microcontroller from different silicon vendors in standard package size LQFP48. It is a clone of the original hobbyist Blue Pill board solderd with either STM32F0 [54] or STM32F1 [55] microcontrollers. Partially, Zephyr upstream boards also exist. See the Links / References column below.

Architecture	Vendor	MCU Series / Line / Type			Clock	Flash	SRAM	Status	Links / References
Arm Cortex-M4	GigaDevice [34]	GD32F30x [51]	GD32F303 [52]	GD32F303CC [53]	120㎒	256㎅	48㎅	❌	WeAct Studio BluePill-Plus [10] STM32-base: BluePill-Plus [13]
Arm Cortex-M3	STMicroelectronics [36]	STM32F1 [55]	STM32F103 [58]	STM32F103CB [61]	72㎒	128㎅	20㎅	✅
				STM32F103C8 [59]	72㎒	64㎅	20㎅
	Geehy [35]	APM32 [38]	APM32F103 [39]	APM32F103CB [39]	96㎒	128㎅	20㎅	❌	WeAct Studio BluePill-Plus-APM32 [14]
				APM32F103C8 [39]	96㎒	64㎅	20㎅
	GigaDevice [34]	GD32F10x [47]	GD32F103 [48]	GD32F103CB [50]	108㎒	128㎅	20㎅		WeAct Studio BluePill-Plus-GD32 [17]
				GD32F103C8 [49]	108㎒	64㎅	20㎅
	WinChipHead [37]	CH32F [40]	CH32F103 [41]	CH32F103C8 [41]	72㎒	64㎅	20㎅		WeAct Studio BluePill-Plus-CH32 [15] BluePill Plus CH32V203
				CH32F103C6 [41]	72㎒	32㎅	10㎅
RISC-V QingKe V3A		CH32V [42]	CH32V103 [43]	CH32V103C8 [43]	80㎒	64㎅	20㎅
				CH32V103C6 [43]	80㎒	32㎅	10㎅
RISC-V QingKe V4B		CH32V [42]	CH32V203 [45]	CH32V203C8 [45]	144㎒	64㎅	20㎅	⚠️
				CH32V203C6 [45]	144㎒	32㎅	10㎅

✅ :

fully supported, no known issues

• STM32F103CB: weact_bluepillplus_stm32f103cb

• STM32F103C8: weact_bluepillplus_stm32f103c8

⚠️ :

not yet completed, as full SoC driver support is missing:

• CH32V203C8: weact_bluepillplus_ch32v203c8

• CH32V203C6: weact_bluepillplus_ch32v203c6

❌ :

not yet supported, as SoC support is missing:

• GD32F303CC: weact_bluepillplus_gd32f303cc

• APM32F103CB: weact_bluepillplus_apm32f103cb

• APM32F103C8: weact_bluepillplus_apm32f103c8

• GD32F103CB: weact_bluepillplus_gd32f103cb

• GD32F103C8: weact_bluepillplus_gd32f103c8

• CH32F103C8: weact_bluepillplus_ch32f103c8

• CH32F103C6: weact_bluepillplus_ch32f103c6

• CH32V103C8: weact_bluepillplus_ch32v103c8

• CH32V103C6: weact_bluepillplus_ch32v103c6

Supported Boards

Hardware

STM32F1CH32V2

The WeAct Studio BluePill-Plus [10] is available with an STM32F103 in two different configurations featuring different sizes of on-chip flash memory. It follows the general BluePill connector concept with two opposing 20-pin headers. The underlying schematic diagram also provides an additional SPI flash (unpopulated). This can be mounted on the bottom of the board at position U3 as an SOIC8 package. It is connected via the first SPI bus, but through pins PA4 to PA7, and thus conflicts with ADC channels 4 to 7, which are located on the same pins as on the BluePill header.

Features and Resources

Printed Circuit Board

5V/480㎃ 3.3V/300㎃ 3.3V(OUT) 72㎒ 64/128㎆ 20㎅ RST BOOT USER BLUE USB-C SWD 5 3 10 2 1 1 1 Single core Arm Cortex-M3 processor running up to 72㎒ 20㎅ on-chip SRAM 64/128㎆ on-chip flash with XIP capabilities USB 1.1 controller (device) CAN 2.0 A/B controller (SOF, 14 filter) On-board USB-C connector On-board 3.3V LDO regulator with 300㎃ On-board RESET button On-board BOOT0 button On-board USER button On-board LED 32 GPIO pins via edge pinout (6 free) 15 PWM channels (3 free) 10 ADC analog inputs 1 UART peripherals 2 I2C controllers 1 SPI controllers 1 Watchdog timer peripheral 1 Temperature sensor on-chip Design Data BluePill-Plus V1.1 Schematic [11] BluePill-Plus V1.0 Schematic [12] STM32-base: BluePill-Plus [13] Remarks Warning: The +5V pins on the board headers are directly connected to the +5V pin of the USB connector via a protective diode. With schematic V1.1, this can be bypassed by a solder bridge (SB1) provided on the bottom directly below the USB-C connector. In this case, do not power this board through USB and an external power supply at the same time! Warning: With schematic V1.1, the series resistor of the user LED (R1) was increased from 1.0kΩ to 1.5kΩ. The power consumption and thus the brightness of the user LED is now slightly lower. Warning: The optional SPI flash (U3) will use the same pins PA4 to PA7 as the BluePill header for ADC channels 4 to 7.

Positions

STM32F1CH32V2

USB Type-C connector Supports USB1.1 slave devices ME6231C33 (VCWK) 300㎃ low dropout, low noise LDO also possible: ME6209A33, ME6216A33, or LN1132P332M STM32F103Cx one of the supported by STMicroelectronics USER LED monochrome user LED for diagnostic (not power indicator) USER button BOOT0 button press it when resetting to enter download mode RESET button SWD Port for flashing and debugging (with 3V3 power supply) On-board SPI flash memory (unpopulated) 4㎆ NOR-Flash W25Q32JV 8㎆ NOR-Flash W25Q64JV 16㎆ NOR-Flash W25Q128JV

Data Sheets

• STM32F1 SoC [55]

• STM32F1 Programming Manual [56]

• STM32F1 Reference Manual [57]

• STM32F103C8 SoC [59]

• STM32F103C8 Datasheet [60]

• STM32F103CB SoC [61]

• STM32F103CB Datasheet [62]

• W25Q32JV [28]

• W25Q32JV Datasheet [29]

• W25Q64JV [30]

• W25Q64JV Datasheet [31]

• W25Q128JV [32]

• W25Q128JV Datasheet [33]

• LN1132P332M [18]

• LN1132 Datasheet [19]

• ME6231C33 [26]

• ME6231 Datasheet [27]

• ME6216A33 [23]

• ME6216 Datasheet V08 [24]

• ME6216 Datasheet V02 [25]

• ME6209A33 [20]

• ME6209 Datasheet V12 [21]

• ME6209 Datasheet V02 [22]

Pinouts

The peripherals of the different populated microcontrollers can be routed to various pins on the boards edge connectors. The configuration of these routes can be modified through DTS. Please refer to the datasheets to see the possible routings for each peripheral. The default assignment is defined below in a single table.

STM32F1CH32V2

Pin Mapping

Pinout

on-board: 1 BUTTON 1 SIGNAL on-header: 5 3 10 2 1 1 1 Default Zephyr Peripheral Mapping   1 SPI2_NSS : PB12 2 SPI2_SCK : PB13 3 SPI2_MISO : PB14 4 SPI2_MOSI : PB15 5 MCO : PA8 nc T1C1 alternative 6 USART1_TXD : PA9 7 USART1_RXD : PA10 8 USB_DM : PA11 9 USB_DP : PA12 10 GPIO_EXTI15/SPI1 : PA15 11 GPIO_EXTI3/SPI1 : PB3 12 GPIO_EXTI4/SPI1 : PB4 nc T3C1 alternative 13 GPIO_EXTI5/SPI1 : PB5 nc T2C2 alternative 14 I2C1_SCL : PB6 15 I2C1_SDA : PB7 16 CAN_RX : PB8 17 CAN_TX : PB9 18 5V 19 GND 20 3V3 21 VBAT 22 GPIO_EXTI13/RTC : PC13 23 GPIO_EXTI14/RTC : PC14 nc on-board OSC32_IN for RTC 24 GPIO_EXTI15/RTC : PC15 nc on-board OSC32_OUT for RTC 25 ADC1_IN1 : PA0 nc on-chip WKUP to exit sleep mode 26 ADC1_IN2 : PA1 27 ADC1_IN3 : PA2 28 ADC1_IN4 : PA3 29 ADC1_IN5 : PA4 30 ADC1_IN6 : PA5 31 ADC1_IN7 : PA6 32 ADC1_IN8 : PA7 33 ADC1_IN9 : PB0 34 ADC1_IN10 : PB1 35 I2C2_SCL : PB10 nc USART3_TXD alternative 36 I2C2_SDA : PB11 nc USART3_RXD alternative 37 NRST 38 3V3 39 GND 40 5V On-Board Mapping for SWD   nc SYS_SWDIO : PA13 nc nc SYS_SWCLK : PA14 nc nc 3V3 nc GND On-Board Mapping for USER and USER   nc GPIO_EXTI2 : PB2 nc on-chip BOOT1 @ 10kΩ pull-down nc GPIO_EXTI0 WKUP : PA0 nc competes with ADC1_IN1 On-Board Routings for SPI Flash (unpopulated)   nc SPI1_NSS : PA4 nc competes with ADC1_IN5 nc SPI1_SCK : PA5 nc competes with ADC1_IN6 nc nc nc SPI1_MISO : PA6 nc competes with ADC1_IN7 nc nc nc SPI1_MOSI : PA7 nc competes with ADC1_IN8 Devicetree compatible nologo,bluepill-header gpio-leds gpio-keys

Supported Features

The WeAct BluePill+ board configuration supports the following Zephyr hardware features:

STM32F1CH32V2

Hardware Features Supported by Zephyr

Peripheral	Kconfig option	Devicetree compatible	Zephyr API
PINCTRL	CONFIG_PINCTRL	st,stm32f1-pinctrl	Pin Control API
GPIO	CONFIG_GPIO	st,stm32-gpio	General-Purpose Input/Output (GPIO)
UART	CONFIG_SERIAL	st,stm32-uart st,stm32-usart	Universal Asynchronous Receiver-Transmitter (UART)
UDC (USB Device Controller)	CONFIG_USB_DEVICE_STACK_NEXT	st,stm32-usb usb-nop-xceiv	USB device support APIs
CAN (L1: PMA / PCS, L2: DLL)	CONFIG_CAN	st,stm32-bxcan	Controller Area Network (CAN) Bus Protocols
I2C	CONFIG_I2C	st,stm32-i2c-v1	Inter-Integrated Circuit (I2C) Bus
SPI	CONFIG_SPI	st,stm32-spi	Serial Peripheral Interface (SPI) Bus
PWM	CONFIG_PWM	st,stm32-timers st,stm32-pwm	Pulse Width Modulation (PWM)
ADC	CONFIG_ADC	st,stm32f1-adc st,stm32-adc	Analog-to-Digital Converter (ADC)
RTC	CONFIG_RTC	st,stm32-rtc	Real-Time Clock (RTC) as Counter
Timer (Counter)	CONFIG_COUNTER	st,stm32-timers st,stm32-counter	Counter
Watchdog Timer (WDT)	CONFIG_WATCHDOG	st,stm32-watchdog st,stm32-window-watchdog	Watchdog
Flash	CONFIG_FLASH	st,stm32f1-flash-controller st,stm32-flash-controller	Flash and Flash map
DMA	CONFIG_DMA	st,stm32-dma-v2bis	Direct Memory Access (DMA)
HWINFO	CONFIG_HWINFO	N/A	Hardware Information
RESET	CONFIG_RESET	st,stm32f1-rcc st,stm32-rcc-rctl	Reset Controller
CLOCK	CONFIG_CLOCK_CONTROL	st,stm32f1-rcc st,stm32f1-clock-mco st,stm32f1-pll-clock st,stm32-hse-clock	Clock Control
NVIC	N/A	st,stm32-exti arm,v7m-nvic	Nested Vector Interrupts Controller
SYSTICK	N/A	arm,armv7m-systick

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

• boards/weact/bluepillplus/weact_bluepillplus_stm32f103c8_defconfig

• boards/weact/bluepillplus/weact_bluepillplus_stm32f103cb_defconfig

Board Configurations

The WeAct BluePill+ boards can be configured for the following different use cases.

STM32F1CH32V2

STM32F103CBSTM32F103C8

west build -b weact_bluepillplus_stm32f103cb -S usb-console

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

west build -b weact_bluepillplus_stm32f103cb

Use the serial port USART1 on edge header as Zephyr console and for the shell.

System and Real-Time Clock

The STM32 system clock (SYSCLK) on the WeAct BluePill+ boards can be driven by an internal or external oscillator, as well as the main PLL clock. By default the system clock is provided by the PLL clock with 72㎒ on STM32F1 or up to 144㎒ on the other counterfeited chips, which is driven by the external (on-board) 25㎒ crystal connected to the high-speed clock input.

The STM32 real-time clock (RTC) on the WeAct BluePill+ boards can be driven by an internal or external oscillator. By default, the real-time clock will be driven by the external (on-board) 32.768㎑ crystal connected to the low-speed clock input.

User LED

The WeAct BluePill+ boards feature one LED for user purposes at GPIO port B line 2 (PB2) in parallel to the BOOT1 signal. The LED is high active.

User Button

The WeAct BluePill+ boards feature one tactile push button for user purposes at GPIO port A line 0 (PA0) in parallel to the WKUP signal and the first ADC channel. The push button is high active.

ADC/TS Ports

The WeAct BluePill+ boards features an 12-bit ADC with 10 external usable channels and, when supported, some additional channels connected internaly to the on-chip temperature sensor (TS), the internal provided voltage reference source (VREF) and the external battery voltage (VBAT) when supported. The ADC channels 0-9 are available on the edge connectors.

SPI Port

The WeAct BluePill+ boards features one five wire SPI bus over SPI2 also available on the edge connectors and the standard pins. SPI1 is not available in any default setup.

I2C Port

The WeAct BluePill+ boards features two I2C buses over at I2C1 and I2C2 also available on the edge connectors and the standard pins. I2C1 is the BluePill standard bus.

CAN Port

The WeAct BluePill+ boards with STM32F1 features one CAN controller, but without any CAN transceiver on board. The bus timing is defined by the DTS and is preset to 1000 kBit/s. The calculation was verified with the help of the CAN Bit Time Calculation Sheet [6] and can also assume smaller bit rates according to the following table. Note that the value of Prescaler, Seg 1 and Seg 2 will be calculated on demand by the Zephyr CAN Controller API together with the driver.

STM32F1CH32V2

CAN bus timing calculation for STM32F1 @ 36㎒

Bit Rate	Sample Point at	Prescaler	Seg 1 (prop-seg + phase-seg1)	Seg 2 (phase-seg2)
1000 kBit/s	88.9 %	2	15	2
800 kBit/s	88.9 %	5	7	1
500 kBit/s	88.9 %	4	15	2
250 kBit/s	88.9 %	8	15	2
125 kBit/s	88.9 %	16	15	2
100 kBit/s	88.9 %	20	15	2
50 kBit/s	88.9 %	40	15	2
20 kBit/s	88.9 %	100	15	2
10 kBit/s	88.9 %	200	15	2

Serial Port

The WeAct BluePill+ boards feature one two wire UART (RxD/TxD) at USART1 and the standard pins (PA9/PA10) to be compatible with the STMicro on-chip bootloader for firmware downloads over UART. The Zephyr console output is assigned to this USART with the default settings of 115200/8N1 without any flow control (no XON/XOFF, no RTS/CTS).

USB Device Port

The WeAct BluePill+ boards with STM32F1 features one (native) USB full-speed 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. This boards provide the Zephyr console per default on the USB port as CDC ACM:

STM32F1CH32V2

USB device idVendor=0483, idProduct=5740, bcdDevice= 4.03
USB device strings: Mfr=1, Product=2, SerialNumber=3
Product: BluePill+ STM32F103 (CDC ACM)
Manufacturer: WeAct (STMicroelectronics)
SerialNumber: 93F49F68D18508F0

Programming and Debugging

Applications for the WeAct BluePill+ board configuration can be built and flashed in the usual Zephyr way (see Building an Application and Run an Application for more details).

Flashing

The WeAct BluePill+ board needs an debug tool adapter, e.g. ST-LINK/V2, SEGGER JLink, Arm CMSIS-DAP or similar.

Flashing an application

Here is an example for the Hello World application.

Run a serial host program to connect with your WeAct BluePill+ board:

user@host:~$ screen /dev/ttyUSBx 115200,cs8,parenb,-parodd,-cstopb,-crtscts

Build and flash the application:

west build -b weact_bluepillplus_stm32f103c8 -p -d build/weact_bluepillplus zephyr/samples/hello_world
west flash -r openocd -d build/weact_bluepillplus

You should see the following message on the console:

*** Booting Zephyr OS build v4.3.0…***
Hello World! weact_bluepillplus_stm32f103c8

Debugging

The SWD interface can also be used to debug the board. To achieve this, you can either use SEGGER JLink, OpenOCD or PyOCD.

You can debug an application in the usual way. Here is an example for the Hello World application:

west build -b weact_bluepillplus_stm32f103c8 -p -d build/weact_bluepillplus zephyr/samples/hello_world
west debug -r openocd -d build/weact_bluepillplus

Tests and Examples

LED Blinky with USB-CDC/ACM Console

STM32F1CH32V2

STM32F103CBSTM32F103C8

west build -b weact_bluepillplus_stm32f103cb -p -S "usb-console" -d build/weact_bluepillplus zephyr/samples/basic/blinky
west flash -r openocd -d build/weact_bluepillplus

memory consumption

[174/174] Linking C executable zephyr/zephyr.elf
Memory region         Used Size  Region Size  %age Used
           FLASH:       45000 B       128 KB     34.33%
             RAM:       14648 B        20 KB     71.52%
           SRAM0:          0 GB        20 KB      0.00%
        IDT_LIST:          0 GB        32 KB      0.00%

Hello Shell

STM32F1CH32V2

STM32F103CBSTM32F103C8

west build -b weact_bluepillplus_stm32f103cb -p -d build/weact_bluepillplus bridle/samples/helloshell -- \
-DEXTRA_CONF_FILE="prj-hwstartup.conf" -DCONFIG_STM32_ENABLE_DEBUG_SLEEP_STOP=y
west flash -r openocd -d build/weact_bluepillplus

memory consumption

[185/185] Linking C executable zephyr/zephyr.elf
Memory region         Used Size  Region Size  %age Used
           FLASH:       57264 B       128 KB     43.69%
             RAM:       16840 B        20 KB     82.23%
           SRAM0:          0 GB        20 KB      0.00%
        IDT_LIST:          0 GB        32 KB      0.00%

References

[1]

https://zephyrproject.org/

[2]

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[3] (1,2,3,4,5,6,7)

https://www.python.org/downloads

[4]

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[5] (1,2)

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[6]

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[7]

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[8] (1,2)

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[9]

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[11]

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[14]

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[43] (1,2,3)

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[45] (1,2,3,4)

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[46]

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[50]

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[51]

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[52]

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[53]

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[54]

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[55] (1,2,3)

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[57]

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[59] (1,2)

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[60]

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[62]

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