Summary of MCP23X08 Evaluation Board using PIC10F202 with Proteus Simulation
MCP23X08 evaluation board PIC10F202 demonstrates GPIO expansion using MCP23008 (I2C) and MCP23S08 (SPI) with bit-banged protocols on a PIC10F202. A toggle switch selects I2C or SPI; the PIC reads upper-nibble inputs from the expander, swaps bits as needed, and mirrors them to lower-nibble LEDs. Fully simulated in Proteus, the project is educational for protocol comparison, dynamic mode switching, and firmware-driven serial communication.
Parts used in the MCP23X08 evaluation board PIC10F202:
- PIC10F202 microcontroller
- MCP23008 I2C I/O expander
- MCP23S08 SPI I/O expander
- LEDs
- Current-limiting resistors for LEDs
- Toggle switch for protocol selection
- Pull-up resistors for I2C lines
- Proteus simulation software (for testing)
Introduction
MCP23X08 evaluation board PIC10F202 is a compact embedded systems project that demonstrates GPIO expansion using MCP23008 and MCP23S08 via I2C and SPI communication. This MCP23X08 evaluation board PIC10F202 uses bit-banged serial protocols on a PIC10F202 microcontroller and is fully simulated in Proteus for educational and protocol comparison purposes.
How the Project Works (Overview)
The PIC10F202 acts as the master controller and dynamically switches between I2C and SPI modes using a hardware toggle switch.
Depending on the selected mode, it communicates with either:
MCP23008 via I2C, or
MCP23S08 via SPI
The microcontroller reads input states from switches connected to the expander and mirrors those inputs onto LEDs. This bidirectional operation highlights real-world serial communication handling using firmware-driven (bit-banged) protocols.
Block Diagram / Workflow Explanation
Mode Selection
A toggle switch selects I2C or SPI communication.Initialization
The PIC initializes GPIO direction registers on both expanders.Input Reading
The upper nibble of the expander GPIO is read as digital inputs.Data Processing
Input bits are swapped to align with LED outputs.Output Driving
The lower nibble drives LEDs to reflect switch states.Continuous Monitoring
The system loops, allowing live switching between I2C and SPI modes.
Key Features
Dual-protocol support (I2C and SPI) using a single microcontroller
Bit-banged serial communication without hardware peripherals
Dynamic mode switching during runtime
GPIO expansion using MCP23x08 devices
Real-time input-to-output mirroring
Fully simulated and testable in Proteus
Components Used
PIC10F202 microcontroller
MCP23008 (I2C I/O expander)
MCP23S08 (SPI I/O expander)
LEDs with current-limiting resistors
Toggle switch for protocol selection
Pull-up resistors for I2C lines
Applications
GPIO expansion in pin-limited microcontrollers
Learning I2C and SPI working principles
Embedded systems training and labs
Communication protocol comparison demos
DIY electronics projects requiring flexible interfaces
Explanation of Code (High-Level)
The firmware is written in MPASM assembly, optimized for the PIC10 architecture.
Key modules include:
I2C routines: Start, Stop, ACK/NACK, byte read/write
SPI routines: Mode 0 clocking, byte transfer, chip-select handling
Mode switching logic: Detects toggle switch state and reconfigures peripherals
GPIO handling: Reads inputs and updates outputs through expander registers
The code carefully manages TRIS behavior since the PIC10F202 lacks a dedicated TRIS register, making this project especially educational.
Source Code
#include; processor specific variable definitions ; #include ; processor specific variable definitions __CONFIG _MCLRE_OFF & _WDT_ON & _IntRC_OSC ; '__CONFIG' directive is used to embed configuration word within .asm file. ; The lables following the directive are located in the respective .inc file. ; See data sheet for additional information on configuration word sett
Proteus Simulation
In Proteus, the simulation allows you to:
Toggle between I2C and SPI modes live
Observe GPIO changes on LEDs instantly
Verify correct ACK/NACK handling
Debug serial timing visually
The simulation behaves exactly like real hardware, making it ideal for learning and troubleshooting without physical components.
(FAQs)
Conclusion
This project is an excellent demonstration of efficient embedded systems design using minimal hardware resources. It shows how a tiny PIC microcontroller can handle complex serial communication, expand GPIO capability, and dynamically manage protocols.
Whether you’re learning Proteus simulation, firmware development, or communication fundamentals, this project delivers strong practical value and real-world relevance.
- How does the project switch between I2C and SPI?
A hardware toggle switch selects I2C or SPI and the PIC10F202 dynamically switches modes in firmware. - Can this project run on real hardware?
Yes, the article states the code is hardware-ready and based on Microchip’s application note. - Why is bit-banging used instead of hardware I2C or SPI?
Because the PIC10F202 does not include built-in serial peripherals. - What expanders are used for I2C and SPI?
MCP23008 is used for I2C and MCP23S08 is used for SPI. - How are inputs and outputs mapped on the expander?
The upper nibble of the expander GPIO is read as inputs and the lower nibble drives LEDs after bit swapping. - What oscillator clock is used for the PIC10F202?
The internal RC oscillator with factory calibration is used. - Why is RAMTRIS used instead of TRIS?
PIC10 baseline devices require manual tracking of pin direction, so RAMTRIS is used. - Can more I/O be added to this design?
Yes; multiple expanders can be chained using address pins according to the article. - Is Proteus used in this project?
Yes, the project is fully simulated and testable in Proteus for live mode switching and debugging. - Is this project suitable for beginners?
The article says yes, but a basic understanding of embedded systems and serial communication helps.
