Serial Pi Zero

RS232 serial interface for the Raspberry Pi Zero

General Info Technical Details Code Libraries and Tutorials

RS232 Port.
Control the Raspberry Pi Zero over RS232 or connect to external serial devices.
Stackable with other Raspberry Pi accessory boards.
Mounting holes for use with the AB Electronics UK mounting kits (sold separately)

The Serial Pi Zero is a communication board supporting the RS232 serial protocol, designed for use on the Raspberry Pi and other compatible single-board computers.

RS232 is widely used for connecting computers to devices such as modems, printers, data terminals and various industrial equipment. Despite being an older technology, it remains prevalent in various legacy systems and industrial applications.

The RS232 port is connected to the GPIO UART port on the Raspberry Pi using a MAX3232 or ICL3232ECBNZ* RS232 transceiver. The RS232 transceiver chip converts the 3.3V UART port to RS232 voltages, allowing communication with RS232 compatible devices over a DB9 serial cable.

With the use of a null-modem cable, the board allows terminal access with Linux on the Raspberry Pi using a terminal application. The RS232 port can be accessed through the DB9 port or the solder points on the PCB.

An array of 2.54mm pitch holes with 3.3V and 5V connections are also provided on the PCB, allowing you to build additional circuits on the board.

Please note that you can only use one Serial Pi Zero board on a Raspberry Pi. If stacking with other boards, we recommend putting the Serial Pi Zero at the top of the stack due to the height of the DB9 connector.

*Due to global component shortages caused by the Covid pandemic, Serial Pi Plus boards manufactured after 23/11/2022 may use the Intersil ICL3232ECBNZ RS232 interface IC. The ICL3232ECBNZ is a pin-compatible replacement for the Texas Instruments MAX3232.

Technical Details

Input Ratings & Specifications

Spec: Ratings
Supply Voltage: 3.3V to 5.5V
Logic Voltage at UART Port: 3.3V
Maximum Data Rate: 250 kbits/s
RS232 Input voltage range: -25V to +25V
RS232 Output voltage range: -13.2V to +13.2V

3D CAD Model

Serial Pi Zero - 3D CAD File (STEP Format)

Schematic

View the schematic PDF.

Mechanical Drawings

Compatibility

We have tested the Serial Pi Zero on the following platforms.

Model	Status
Raspberry Pi Model A / B
Raspberry Pi 1 Model A+ / B+
Raspberry Pi 2 Model B
Raspberry Pi 3 Model A+ / B / B+
Raspberry Pi 4 Model B
Raspberry Pi 5
Raspberry Pi Zero
Raspberry Pi Zero W / Zero 2 W
Raspberry Pi Compute Module 4 IO Board
Raspberry Pi 400
Orange Pi
Odroid

*You need to use the latest Raspberry Pi OS release and disable the built-in Bluetooth to use the Serial Pi Zero on the Raspberry Pi 3, 3+ and 4. See our Serial Port Tutorial for the config changes needed.

Assembly Instructions

This product requires a soldering iron and solder to fit the connectors.

The Serial Pi Zero is supplied with the 40-pin GPIO connector, and the DB9 male connector unsoldered.

Before using the Serial Pi Zero, you need to solder both connectors onto the PCB. We suggest soldering the 40-pin GPIO connector first and then the DB9 connector.

To make assembly easier, we have designed a PCB header assembly jig which you can download and print.

Watch the assembly video for the Serial Pi Plus, which uses the same assembly steps as the Serial Pi Zero.

Watch our assembly guide on YouTube. (opens in a new window)

PCB Header Assembly Jig

Download and print our PCB Header Assembly Jig to hold your circuit board when soldering the header pins.

RS232 Port

RS232 port pin-out connections
Pin	Usage
1	N/C
2	RX (data receive)
3	TX (data transmit)
4	N/C
5	Ground
6	N/C
7	N/C
8	N/C
9	N/C

DB-9 Connector

DB9 connector as viewed from the front of the Serial Pi Plus

Using the RS232 port for terminal connections

The RS232 port can be used for remote terminal connections on the Raspberry Pi, allowing remote access and control without needing an Ethernet connection. You must use a Null-Modem cable to connect the Serial Pi to a desktop computer. A wiring diagram for making a Null-Modem cable can be found below. For details on configuring the RS232 communication on the Raspberry Pi, visit our knowledge base.

Null-Modem Cable

Null modem wiring diagram

Null Modem connections
Connector 1	Connector 2	Function
2	3	Rx ← Tx
3	2	Tx → Rx
5	5	Ground

Datasheets

Ti MAX3232E

ICL3232ECBNZ

Serial Pi Zero Articles & Tutorials

Soldering Service

This product requires a soldering iron and solder to fit the connectors.

We offer a convenient and reliable soldering service, allowing you to purchase our boards ready assembled to connect to your Raspberry Pi. *

Add Soldering Service

£2.99
ex VAT

Note: If you are purchasing additional connectors for your expansion board and would like us to solder them to the PCB, please contact us after placing your order or add a note with your requirements at the checkout.

* excluding trade orders.

EU Orders

EU orders less than €150 include VAT at your countries rate, and are free from additional import fees under our IOSS registration.

Product Code: Serial Pi Zero

EAN: 7426787870200

Free delivery on orders over £35 ex VAT

Mounting Kit Four Pack

Mounting kit to use on our Raspberry Pi boards

£3.49 ex VAT

RS485 Pi

RS485 serial interface development board for the Raspberry Pi

£11.99 ex VAT

Serial Pi Plus

RS232 Serial Port development board for the Raspberry Pi

£10.99 ex VAT

Important Information

This development board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by abelectronics.co.uk to be a finished end-product fit for general consumer use. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. Persons handling the product(s) must have electronics training and observe good engineering practice standards. This development board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives or other related directives. Note: documents in Portable Document Format (PDF) require Adobe Acrobat Reader 5.0 or higher to view, download Adobe Acrobat Reader or other PDF reading software for your computer or mobile device.