Blue Pill
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| Manufacturer | Various |
|---|---|
| Host port | USB Micro B (varying quality) |
| Microcontroller | STM32F103 |
| MPU | ARM Cortex-M3 |
| Voltage | 3.3 V |
| Clock speed | 72 MHz |
| Digital I/O pins | 32 |
| I/O Voltage | 3.3 V |
| RAM | 20 KB |
| Program memory | 64 KB |
| Boot loader | None |
Blue Pill and Red Pill are nicknames for a common microcontroller board with STM32F103 microcontrollers, having blue and red soldermask, respectively.
The red boards were probably the original, made by an unknown manufacturer. They has only the marking "JC66 STM32F103C8 CoreBoard".
Clones with blue soldermask have been made by multiple manufacturers, and have been popular because they have been common and very cheap.
Description[edit | edit source]
The microcontroller is a STM32F103, running at 72 MHz, with 64 KB Flash and 20 KB RAM.
The board's format is similar to that of a 40-pin DIP package but the board is typically somewhat wider to have space for printing pin numbers.
Has a 32 khz real-time clock crystal.
It has a reset button. There is a four-pin SWD header on the short edge.
There are two header pin triplets with jumpers, for enabling programming over SWD.
Shortcomings[edit | edit source]
Some variants have addressed these shortcomings: see variants below.
- The pull-up resistor (R10) on the USB D+ is often of the wrong value: either 10 kΩ or 4.7 kΩ. To comply with the USB standard and work with more hardware, it should be replaced with a resistor of 1.5 kΩ or get an additional resistor in parallel.
- It does not come with a USB bootloader, so SWD must be used to program the device with firmware or a bootloader.
- The Micro USB port is often just surface-mounted, and therefore easily broken.
- The voltage regulator is capable of supplying no more than 100 mA to external devices. It otherwise overheats easily.
- There is no diode from VBUS to the board's +5V pin, so you can't have it connected via USB and get +5V from an external source at the same time.
- There is no reference-power for the analog-to-digital converters.
- There are components on both sides of the board.
Pinout[edit | edit source]
| Function | Pin | ↑ | Pin | Function |
|---|---|---|---|---|
| CK3,NSS2 | PB12 | USB | GND or VBUS | |
| CTS3,SCK2 | PB13 | GND | ||
| RTS3,MISO2 | PB14 | +3.3V | ||
| MOSI2 | PB15 | NRST (Reset) | ||
| CK1 | PA8 | PB11 | SDA2,RX3 | |
| TX1 | PA9 | PB10 | SCL2,TX3 | |
| RX1 | PA10 | PB1 | ADC9 | |
| CTS1 | PA11 | PB0 | ADC8 | |
| RTS1 | PA12 | PA7 | ADC7,MOSI1 | |
| NSS1 | PA15 | PA6 | ADC6,MISO1 | |
| SCK1 | PB3 | PA5 | ADC5,SCK1 | |
| MISO1 | PB4 | PA4 | ADC4,NSS1,CK2 | |
| MOSI1 | PB5 | PA3 | ADC3,RX2 | |
| TX1,SCL1 | PB6 | PA2 | ADC2,TX2 | |
| RX1,SDA1 | PB7 | PA1 | ADC1,RTS2 | |
| SCL1 | PB8 | PA0 | ADC0,CTS2 | |
| SDA1 | PB9 | PC15 | ||
| +5V (VBUS) | PC14 | |||
| GND | PC13 | |||
| +3.3V | VBAT | |||
Notes:
- One pin is GND or VBUS depending on board model.
- The +5V line is connected directly to VBUS
- User LED is on PC13, lit when PC13 is low.
- The four-pin SWD port on the short edge is not shown in this diagram.
Variants[edit | edit source]
RobotDyn STM32 Mini[edit | edit source]
It is often called the RobotDyn Black Pill because of its black solder mask, and must not be confused with other black STM32 boards also called "Black Pill" such as the one from WeAct Studio.
- It has a diode from VBUS and a more capable power regulator.
- The Micro USB port is through-hole soldered and the pull-up resistor has the correct value.
- The board is also narrower.
External links:
- STM32duino Forum Wiki—RobotDyn Black Pill
- STM32-base—RobotDyn Black Pill
WeAct Studio BluePill Plus[edit | edit source]
Multiple variants:
| µC | Clock | SRAM | Flash |
|---|---|---|---|
| STM32F103C8T6 | 72 MHz | 20 KB | 64 KB |
| GD32F303CCT6 | 120 MHz | 48 KB | 256 KB |
They are licensed under GPL version 3.
- Has a USB C port.
- The jumpers have been removed, instead having a BOOT0 button that must be held for 0.5s during reset.
- The user LED is on PB2, active high.
- A user button on PA0.
- Diode from VBUS to VCC, allowing external power while plugged in via USB. The +5V pin is connected to VCC.
- The GND pin nearest the USB port's short edge has been changed into an additional VCC.
- The bottom is flat, with pads for an optional W25Q32JVSSIQ SPI flash chip.
- Realtime clock has been removed.
External links:
- WeAct on GitHub—BluePill Plus / WeAct Studio 微行工作室 出品
External links[edit | edit source]
Trivia[edit | edit source]
The nicknames "Blue Pill" and "Red Pill" are a reference to the movie The Matrix (1999). They were coined on the STM32duino forum.
