Single board Pimoroni Pico LiPo: like a Raspberry microcontroller, only better

After the Raspberry Pi Foundation developed and announced its RP2040 processor, several single-board based on it appeared on the market, including its own development Raspberry. Notable RP2040 projects include Adafruit Py RP2040 and Pimoroni Tiny 2040. There is also Adafruit Feather RP2040 with Cytron Maker Pi Pico.

Recall that the Raspberry Pi Pico project itself is, in fact, a microcontroller with GPIO and programmability. The board can be used to emulate a wide variety of interface types, including retro systems. Raspberry’s Pico has a relatively small feature set, but it’s worth the price. Now there is a new device called Pimoroni Pico LiPo. It’s like “Pico on steroids”.

Its cost is $ 17, that is, 4 times more than the original Pico. But the possibilities are wider, so the device can be useful to those developers who lacked the capabilities of the Raspberry microcontroller. So, there is a battery charging function, a USB-C port, 16 MB of flash memory and a Stemma QT / Qwiic connector.

More about the characteristics

System on a Chip RP2040
Dual-core Arm Cortex M0 +, 133 MHz.
264KB SRAM, and 4 / 16MB Flash memory
GPIO 26 × multifunctional 3.3V GPIO pins
2 × SPI, 2 × I2C, 2 × UART, 3 × 12-bit ADC, 16 × PWM channels
1 x User LED (GPIO 25)
8 × Programmable I / O (PIO) state machines for custom peripheral support.
Stemma QT / Qwiic connector
SWD debug breakout
The module can be soldered on boards
Power USB C for data and power
2 pin JST connector for LiPo / Li lon batteries. Battery monitoring + LED to display the battery working mode.

Design and use of Pimoroni Pico LiPo

Pico LiPo works perfectly with MycroPython. To get the most out of your board, you need to use CircuitPython, especially when working with Stemma QT / Qwiic components. If for some reason you need to work with MicroPython and at the same time interact with Stemma QT / Qwiic devices, then you should try the latest project from Adafruit. Here can be downloaded everything you need works with Pico LiPo quite smoothly.

As stated above, the Pico LiPo is a steroid-powered Raspberry Pi Pico. With the same size and similar GPIO pinout, the device has a battery charging function, Stemma QT / Qwiic and a power button. The most important feature is battery charging. The charging mode is controlled by the MCP73831 chip. The current is small – 215 mA, but during the LiPo test the battery was fully charged.

There is battery protection – XB6096I2S, which prevents possible overcharging. There is no dedicated MicroPython or CircuitPython module for charge monitoring. To determine the fact of charge, the 24th pin is used. And for monitoring – the 29th. In total, the device has three analog inputs – the same as the “raspberry”, but less than the Adafruit’s Feather RP2040. Yes, one pin less, but if you take into account that it is used to control the battery charge, then it is easier to come to terms with the loss.

The positive point in this is the ability to use the battery as a basic uninterruptible power supply. So, the project can be powered from USB-C, but if the power goes out, the battery comes into play. The pinout of the Pico LiPo is the same as that of the “raspberry”. Plus there is a Stemma QT connector, thanks to which connecting an external device becomes a very simple task.

The presence of this connector is a real breakthrough for I2C devices. The fact is that a number of manufacturers have many compatible components, including temperature sensors, capacitive inputs, screens, etc. Using a capacitive touch sensor MPR121 and the latest version of CircuitPython 7 for Pico LiPo, we created a demo system using the Stemma QT connector.

The system started working immediately and without any problems. In addition, we see many projects using Stemma QT / Qwiic. There is a three-pin JST-SH connector next to this connector – this is debug. The pins are used to receive data from a running RP2040 without using a UART. Using these pins and another Pi Pico as a debug host, we can work with CPU, SRAM, mapped I / O memory in the development environment of our choice. If you are developing mission-critical RP2040 applications, this is a key feature. Well, for most of us, it’s just an interesting feature.

Power button – toggle switch. It doesn’t sound particularly exciting, but there are a couple of important points here. The fact is that it is this button that allows you to completely de-energize the power, and not just perform a reset. Well, since we have a battery, its charge can be saved by completely disconnecting the board. With a button of another type, this number will not work – the battery will continue to discharge. When the board is needed again – just turn on the button and that’s it.

The BOOT button is usually used to enter the system into firmware mode. But this board still has the ability to use a button in the code. There are three different LEDs on the board, including power, battery charge status, and a custom LED connected to pin 25.

As mentioned above, the board’s pinout is the same as that of the “raspberry”, so you can use it exactly where the Raspberry Pi Pico is used. If desired, this microcontroller can be replaced with LiPo in an already finished project and get more functions. We verified this statement by replacing the Raspberry microcontroller with a new board in this project. After the replacement, everything worked without dancing with a tambourine.

Use cases for Pimoroni Pico LiPo

The LiPo has everything the Raspberry Pi Pico gives, plus additional features. Even the ability to connect the battery alone is worth the $ 17 developers ask for their microcontroller. It can be used in a wide variety of projects, from NeoPixel-powered lightsabers to the Internet of Things. Pico LiPo can be used in various robotic projects, but for servos, motors, etc. you will need your own power supply – the GPIO of the board will not supply current more than 600 mA.

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