Introduction
Hookup Guide
Introduction
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SparkFun Thing Plus - RP2350
SKU:
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The SparkFun Thing Plus - RP2350 is a dynamic and powerful wireless development platform in the Thing Plus form factor. Built around the RP2350 microcontroller from the Raspberry Pi Foundation, this board includes their radio module for single-band 2.4 GHz WiFi 4 (802.11n) and Bluetooth® 5.2 along with common hardware components found on all Thing Plus Boards. This includes on-board Lithium Ion (LiPo) battery charging and fuel gauge circuits, µSD card socket, Qwiic connector, and the Thing Plus pinout allowing use of the Thing Plus - RP2350 in a wide variety of both local and remote applications.
The Raspberry Pi Radio Module (RM2) operates over an SPI interface, and we've designed this board to use the same pins for the radio module as official Raspberry Pi boards, making it easy to use the radio module without having to adjust anything from those development boards. The RP2350 Thing Plus includes two expanded memory options: 16MB of external Flash and 8MB PSRAM connected to the RP2350's QSPI controller. This Thing Plus board works with C/C++ using the Pico SDK, MicroPython, CircuitPython, and Arduino development environments.Purchase from SparkFun
Required Materials
To follow along with this guide you will need at least one USB-C cable to connect the Thing Plus to your computer:
You may also want to get a Qwiic cable or kit to connect the Thing Plus - RP2350 to other Qwiic devices:
Optional Materials
The Thing Plus - RP2350 includes a 2-pin JST connector and integrated charging circuit for an attached single-cell LiPo battery. Below are a few options we recommend for battery-powered applications:
If you prefer a soldered connection or want to modify the solder jumpers on this board, you may need some of the products listed below:
Suggested Reading
We designed this board for integration into SparkFun's Qwiic connect system. Click on the banner below to learn more about the SparkFun Qwiic Connect System.
Before getting started with this Hookup Guide, you may want to read through the tutorials below if you are not familiar with the concepts covered in them or want a refresher. If you are using either of the Qwiic Shields linked above, we recommend reading through their respective Hookup Guides before continuing with this tutorial:
Hardware Overview
Let's take a closer look at the RP2350 and other hardware components on this Thing Plus board.
RP2350 Microcontroller
The RP2350 from Raspberry Pi packs a whole lot of computing punch in a tiny package. The RP2350 is a unique dual-core microcontroller that has four internal processors (two Arm Cortex-M33 and two Hazard3 RISC-V processors @150 MHz), though you can only select any two of these four to run at the same time.
This internal configuration allows users to customize the chip to use a pair their preferred architecture (ARM or Hazard3) or to use one of each! The RP2350 includes 520kB of on-chip SRAM in ten independent banks, 8kB of one-time-programmable (OTP) storage and this board also includes PSRAM connected to the chip's QSPI bus. The RP2350 also has a bevy of security features including optional boot signing with protected OTP storage for the boot decryption key, global bus filtering (based on either Arm or RISC-V security and privilege levels) and more.
The Thing Plus - RP2350 uses the "A" version of the microcontroller which has 30 5V-tolerant GPIO with 4 analog inputs and also includes the following peripheral options:
- 2x UART
- 2x SPI
- 2x I2C
- 24 PWM
- USB 1.1 Controller
- 12 PIO State Machines
- 1x High-Speed Transmit (HSTX) Peripheral for DVI/DSI support
For complete information on the RP2350, refer to the datasheet.
Memory
W25Q128 Flash
The W25Q128 Flash IC adds 16MB of storage space on the Thing Plus. This connects to the RP2350 over QSPI.
PSRAM
The board also includes an 8MB PSRAM IC for dynamic storage. This also connects to the RP2350 over QSPI. PSRAM support is included in the SparkFun MicroPython "early release" firmware found later in this guide and on the product page, but is not natively supported in the Pico SDK as of release. Refer to the Arducam Demo section of this guide for information on how to enable and set up PSRAM using the Pico SDK.
For a complete overview of the PSRAM IC, refer to the datasheet.
µSD Card Slot
The board has a µSD card slot that connects to the RP2350's SPI bus for even more storage. Make sure the SPI are LOW when the µSD card is unpowered. Setting these pins HIGH can damage the GPIO pins. The connector is a fricton-fit connector so no "clicking" and "unclicking" is necessary. Just plug it in nice and snug.
Raspberry Pi RM2 Radio Module
The Raspberry Pi RM2 (radio module 2) is built around the same chipset as the previous Raspberry Pi radio module found on boards like the Pico W. The module features both WiFi 4 (802.11n) 2.4GHz and Bluetooth™ 5.2 with support for Low Energy (Central and Peripheral) and Classic.
The RM2 communicates with the RP2350 over SPI and we've designed this board to use the same pins for the radio module as official Raspberry Pi boards (Pico W and Pico 2 W), making it easy to use the radio module without having to adjust anything from those development boards. The Thing Plus routes the module's GPIO0 pin to a blue STAT LED to allow users to create a visual indicator of the status of the module. We added this STAT LED connected to the same pin used on the Pico W to make code for that compatible with the Thing Plus - RP2350.
Power Components
The Thing Plus - RP2350 includes several options for powering including USB-C, LiPo battery with on-board battery charging and monitoring circuits as well as direct power inputs.
USB-C Connector
The USB-C connector on the board acts as the primary serial interface for the RP2350 as well as a power input. The 5V USB input voltage is regulated down to 3.3V through a voltage regulator with a max current of 500mA@3.3V.
2-Pin JST Connector, Battery Charger, & Fuel Gauge
Want some LiPo battery care tips?
Check out our Single Cell LiPo Battery Care tutorial for some helpful tips on handling and caring for them.
The board has a 2-pin JST connector to connect a single-cell Lithium Ion (LiPo) battery for battery-powered applications. It also has an MCP73831 battery charger to charge an attached battery and a MAX17048 fuel gauge to monitor battery voltage levels. The charge rate is set to 214mA@3.3V. The MCP73831 receives power from the V_USB line so it only is powered when 5V is provided either over USB or the V_USB PTH pin. If applying voltage directly to the V_USB pin make sure it does not exceed 5.5V.
The MAX17048's I2C lines are pulled up to 3.3V_P to allow for customizable power options. Read on below for more information about peripheral power.
Peripheral Power Control
The board includes a second RT9080 3.3V regulator to control power to the peripheral 3.3V (3.3V_P) rail. This is powered on by default with some options for user control to help conserve power. The RT9080's EN (Enable) pin is tied to GPIO13 so users can drive it LOW in their code to disable this line. It also is tied to the main 3.3V rail through the LP solder jumper so it defaults to powered on. If this solder jumper is opened, it defaults to off when the RP2350 is power-cycled though users can drive the GPIO13 pin HIGH in their code to enable the 3.3V_P rail.
Pinout & Qwiic Connector
Thing Plus boards break out a large number of GPIO and interface pins to a pair of 0.1"-spaced plated through-hole (PTH) headers and also has a Qwiic connector for easy integration into SparkFun's Qwiic ecosystem.
Qwiic Connector
The Qwiic connector is tied to GPIO6 (SDA) and GPIO7 (SCL) pins on the RP2350. The Qwiic connector provides connections for SDA, SCL, 3.3V, and Ground. Note, the Qwiic connector power and I2C pins are tied to 3.3V_P and are powered by default but if the peripheral power control circuit is adjusted as covered above, it will not function properly without enabling 3.3V_P through code.
PTH Headers
The Thing Plus's pair of PTH headers break out a selection of 21 GPIO pins from the RP2350 along with PTH connections to USB voltage (5V), regulated 3.3V, battery voltage, RP2350 reset signal, and the voltage regulator Enable pin. The board also has a "central" row of three 0.1"-spaced headers connected to the RP2350's internal Serial Wire Debug multi-drop bus.
The pinout includes connections to UART, I2C, SPI, 13 GPIO (3 of analog-capable pins) and the WS2812's DATA OUT pin.
Buttons
There are two buttons on the board labeled RESET and BOOT. The RESET button is tied to the RP2350's RUN pin and resets the IC when pressed. The BOOT button puts the RP2350 into bootloader mode when held down during power on or reset. Read on to the UF2 Bootloader section of this guide for more information on using the bootloader.
LEDs
The Thing Plus - RP2350 includes three labeled LEDs; PWR, CHG and STAT as well as a WS2812 RGB LED.
The red PWR LED indicates when the 3.3V rail is powered. The yellow CHG LED indicates when the charge circuit is powered with 5V from either the USB-C connector or the V_USB PTH pin. The blue STAT LED is tied to the RM2 radio module GPIO0 to be used for indicating when the module is transmiting/receiving data. The WS2812 RGB LED's DATA IN pin is tied to the RP2350 GPIO14 pin. The RGB LED's DATA OUT pin is routed to the FREEBIE PTH (labeled LED on the board) if users want to daisy-chain more LEDs to the board.
Jumpers
Never modified a jumper before?
Check out our Jumper Pads and PCB Traces tutorial for a quick introduction!
This Thing Plus has four solder jumpers labeled PWR, I2C, LP, and SHLD.
The PWR jumper completes the Power LED circuit and is CLOSED by default. Open the solder jumper by severing the trace in between the two pads to disable the Power LED if needed.
The I2C jumper pulls the I2C lines (SDA/SCL) to 3.3V through a pair of 2.2kΩ resistors. This three-way jumper is CLOSED by default. Open the solder jumper to disable the pullup resistors on the I2C bus if needed.
The LP jumper controls whether the peripheral power regulator is always on or toggleable with an I/O pin (RP2350 GPIO13). This jumper is CLOSED by default so all peripherals (Qwiic connector, µSD slot and RGB LED) are always powered on. Opening this jumper requires setting GPIO13 HIGH to enable peripheral power.
The SHLD jumper connects the USB-C connector's shield pin to the board's ground plane. This jumper is CLOSED by default. Open it to isolate the shield pin from the board.
Board Dimensions
This board matches the Thing Plus footprint and measures 2.3" x 0.9" (58.42mm x 22.86mm) and includes four mounting holes that fit a 4-40 screw. Note, the RM2 antenna comes very close to the "top" two mounting holes so take care when securing anything to these holes to avoid damaging the radio's antenna.
Need more measurements?
For more information about the board's dimensions, users can download the Eagle files for the board. These files can be opened in Eagle and additional measurements can be made with the dimensions tool.
Eagle - Free Download!
Eagle is a CAD program for electronics that is free to use for hobbyists and students. However, it does require an account registration to utilize the software.
Dimensions Tool
This video from Autodesk demonstrates how to utilize the dimensions tool in Eagle, to include additional measurements:
Hardware Assembly
Qwiic Assembly
Basic assembly of the Thing Plus - RP2350 just requires plugging the board in over USB-C to upload firmware and/or start programming with it. SparkFun offers a variety of Qwiic breakout boards with Python libraries like the AS6212 Temperature Sensor Breakout connected to the board in the photo below:
Soldered Assembly
New to soldering?
If you have never soldered before or need a quick refresher, check out our How to Solder: Through-Hole Soldering guide.
Users looking to start prototyping with the Thing Plus plugged into a breadboard should solder a pair of male or stackable headers.
UF2 Bootloader
The Thing Plus - RP2350 uses a UF2 bootloader for easy flashing/uploading of code to the board. The UF2 bootloader causes the board to show up on your computer as a USB storage device and does not require any drivers for Windows, Mac OSX, and Linux! This bootloader is used for uploading in both the Pico SDK and MicroPython development environments so let's take a brief look at how to enter bootload mode.
What is UF2?
UF2 stands for USB Flashing Format, which was developed by Microsoft for PXT (now known as MakeCode) for flashing microcontrollers over the Mass Storage Class (MSC), just like a removable flash drive. The file format is unique, so unfortunately, you cannot simply drag and drop a compiled binary or hex file onto the board. Instead, the format of the file has extra information to tell the processor where the data goes, in addition to the data itself. For more information about UF2, you can read more from the MakeCode blog, as well as the UF2 file format specification.
Entering the Bootloader
Putting the Pro Micro - RP2350 only requires a couple of presses of the BOOT and RESET buttons. Start by pressing and holding the BOOT button down:
Next, press and release the RESET button while still holding down the BOOT button:
Finally, release the BOOT button and the board should be in bootloader mode and appear on your computer as a USB storage device called "RP2350".
Pico SDK Setup
Raspberry Pi Pico SDK
The Pico C SDK is a C/C++ development kit for Raspberry Pi microcontrollers including the RP2350. Click on the links below for complete documentation on installing and using the SDK.
Thing Plus - RP2350 Board Definition
As of release, the Thing Plus - RP2350 does not have it's own board definition in the Pico SDK. Until this definition is added in what should be v2.1 of the SDK, users should select Pico 2 for their board when uploading to the Thing Plus. We recommend using Microsoft Visual Studio with the Pico SDK Extension in the meantime.
MicroPython Setup
Setup
MicroPython is an application of the Python 3 language that runs on microcontrollers like the Thing Plus - RP2350 that allows you to easily interact with the board directly over a USB serial interface through either a command line interface or your preferred Python IDE such as Thonny. We'll do a quick overview of how to download MicroPython firmware on to the Thing Plus - RP2350 but for a complete overview of using MicroPython with this and other RP2350 boards, head over to Raspberry Pi's documentation by clicking the button below:
UF2 Firmware
As of this writing, we're waiting on the next release of MicroPython to include UF2 files for the Thing Plus - RP2350 so to get users started before then, we have a Beta release of MicroPython firmware available here. You can also go directly to the Beta 04 release by clicking the button below:
Once downloaded, put the Thing Plus - RP2350 into UF2 bootloader mode and open the location the board appeared as a USB storage device (it should appear as "RP2350"). Next, simply drag and drop the UF2 file into the RP2350 folder and the board should reboot. After the board reboots, open up your preferred MicroPython IDE (or command line interface) and you can start interacting with your Thing Plus. Read on to the MicroPython examples section for a few quick examples to make sure everything is working properly.
CircuitPython Setup
Setup
The Thing Plus - RP2350 is included in the latest release of CircuitPython. If you've never used CircuitPython before, take a read through their tutorial here or click the button below:
Thing Plus - RP2350 Firmware
Download the latest firmware for the Thing Plus - RP2350 from the CircuitPython downloads page and search for "Thing Plus RP2350".
Arduino Setup
Attention
If this is your first time using Arduino, please read through our tutorial on installing the Arduino IDE. If you have not installed an Arduino library before, we recommend you check out our installation guide.
Arduino-Pico Boards
The SparkFun Thing Plus - RP2350 is supported on the Arduino IDE in the Arduino-Pico boards package. To install the package, open the Preferences menu by navigating to File > Preferences. Look at the bottom of the Preferences menu for "Additional boards manager URLS" and then copy this JSON link into that field:
https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
Click "OK" to close this menu then navigate to the Boards Manager tool and search for "pico" and download the latest release of "Raspberry Pi Pico" (4.0.1 or later).
For more information on using the Arduino-Pico boards package, check out their documentation page.
MicroPython Examples
Verify MicroPython Firmware & Hardware
First, to make sure everything is running properly, use the sys module to verify the firmware version and machine/board running. Open your preferred interface and enter the following prompts and you should see something similar to the printout below:
import sys
sys.implementation
(name='micropython', version=(1, 24, 0, 'preview'), _machine='SparkFun Thing Plus RP2350 with RP2350', _mpy=7942)
Verify Memory (Internal and PSRAM)
Next, we can verify the total free memory on the Thing Plus which includes the built-in memory on the RP2350 as well as the 8MB PSRAM. We'll use the gc module for this so type in the prompt below and you should see a response close to the value below:
WS2812 LED Control
Now let's make sure we can properly control the WS2812 LED on the Thing Plus using the machine and neopixel classes. The WS2812 Data In pin connects to I/O 14 but we've defined this pin as "NEOPIXEL" which takes care of assigning the pin and defining it as an output. Next, we'll set the color to red and finally write the color values to the LED. The code below goes through all these steps so try copying it on your machine and you should see the WS2812 LED turn red.
import machine, neopixel
pin = machine.Pin("NEOPIXEL")
led = neopixel.NeoPixel(pin, 1)
led[0] = (255, 0, 0)
led.write()
Try playing around with other values between 0 and 255 for the three colors (R, G, B) and then writing the changes to switch the LED's displayed color.
Network Test
Finally, let's run an example to test connecting the Thing Plus - RP2350 to a WiFi network, then access an API and print out the data returned. This example polls a database maintained here that lists the number and names of astronauts currently on the ISS and then prints them out. The code also includes some helpful RGB status colors to indicate when the board is connecting to WiFi (RED), downloading data (BLUE), and on success (GREEN).
Before running the example, adjust the template values in the example called WIFI_NETWORK and WIFI_PASSWORD with your WiFi network ID and password.
import network
import urequests
import time
import neopixel
import machine
# Set up the NeoPixel LED
pin = machine.Pin("NEOPIXEL")
led = neopixel.NeoPixel(pin, 1)
# Set the LED to red while connecting to WiFi
led[0] = (255, 0, 0)
led.write()
# Connect to a WiFi network
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect('WIFI_NETWORK', 'WIFI_PASSWORD')
# Wait for the connection to complete
print("Waiting for connection...")
while not wlan.isconnected():
time.sleep(1)
print('.', sep='', end='', )
print('Connected!')
# Set the LED to blue while downloading data
led[0] = (0, 0, 255)
led.write()
# Download the list of astronauts currently in space
print('Downloading list of astronauts currently in space...')
astronauts = urequests.get("https://corquaid.github.io/international-space-station-APIs/JSON/people-in-space.json").json()
# Print the number of astronauts and their names
number = astronauts['number']
print('There are', number, 'astronauts in space.')
for i in range(number):
print(i+1, astronauts['people'][i]['name'])
# Set the LED to green to indicate success
led[0] = (0, 255, 0)
led.write()
Arduino Examples
Troubleshooting
[SparkFun Technical Assistance Page](https://www.sparkfun.com/technical_assistance){ .md-button .md-button--primary }
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Resources:
Resources
For more resources related to the
- Product Page
- Schematic (PDF)
- Eagle Files (ZIP)
- Board Dimensions (PNG)
- SparkFun Pico SDK Library
- Arduino Pico Arduino Core
- MicroPython Firmware (Beta 04)
- MicroPython Documentation
- CircuitPython Downloads
- RP2350 Product Brief
- Raspberry Pi RP2350 Microcontroller Documentation
- Qwiic Info Page
- Datasheet (RP2350)
- Datasheet (APS6404L PSRAM)
- Hardware GitHub Respository