Serial Communication Examples

This section covers serial communication examples that have been tested and verified on PY32F0xx hardware.

Overview

The PY32F0xx HAL includes two comprehensive serial communication examples:

1. Serial Echo - Basic USART communication
2. Serial ADC - Advanced serial + ADC integration

Both examples are confirmed working on PY32F003I DFN8 package at 9600 bps.

Key Features

Verified Configuration

• USART2: PA0=TX(AF9), PA1=RX(AF9)
• Baud Rate: 9600 bps
• Clock: 24MHz HSI (reliable configuration)
• Debug LED: PB5 for visual feedback

Hardware Tested

• Device: PY32F003I DFN8 package
• Programmer: PyOCD with ST-Link compatible
• Serial: USB-to-Serial adapters (multiple tested)

Quick Start

Build and Flash

# Serial echo example
make flash EXAMPLE=serial_echo MCU_TYPE=py32f003xx4

# Serial ADC example
make flash EXAMPLE=serial_adc MCU_TYPE=py32f003xx4

Connect Serial Terminal

# Using screen
screen /dev/ttyACM0 9600

# Using minicom  
minicom -D /dev/ttyACM0 -b 9600

Pin Configuration

PY32F003I DFN8 Package

            DFN8 Pinout (Top View):
               VCC  1 ┌─────┐ 8  PB5/LED
               PA0  2 │     │ 7  PA14-SWDCK/PB6
               PA1  3 │     │ 6  PA13-SWDIO/PA10
               PA2  4 └─────┘ 5  PB0/PF2-NRST

Connections

Technical Implementation

Clock Configuration

Both examples use the same reliable clock setup:

#![allow(unused)]
fn main() {
let rcc = p.RCC
    .configure()
    .hsi(HSIFreq::Freq24mhz)  // 24MHz HSI
    .sysclk(24.MHz())         // System clock
    .freeze(&mut p.FLASH);
}

USART Setup

The key to success is using AF9 alternate function:

#![allow(unused)]
fn main() {
let tx = gpioa.pa0.into_alternate_af9(); // TX
let rx = gpioa.pa1.into_alternate_af9(); // RX

let serial = Serial::usart2(
    p.USART2,
    (tx, rx),
    9600.bps(),
    clocks,
);
}

Debug LED

Visual feedback with PB5:

#![allow(unused)]
fn main() {
let mut led = gpiob.pb5.into_push_pull_output();
led.set_high().ok(); // LED on for activity
}

Example Comparison

Testing Tools

Python Test Script

You can quickly verify serial communication using a Python script, for example, test_serial.py:

import serial
import time

# Connect to device
ser = serial.Serial('/dev/ttyACM0', 9600, timeout=1)

# Test echo
ser.write(b'Hello PY32F0xx!\n')
response = ser.read(50)
print(f"Response: {response}")

# For ADC example
ser.write(b'h')  # Get help
ser.write(b'r')  # Read ADC
ser.write(b's')  # Start streaming
time.sleep(5)
ser.write(b'q')  # Stop streaming

Manual Testing

# Connect to device
screen /dev/ttyACM0 9600

# For serial_echo.rs:
# Type any characters, they should echo back

# For serial_adc.rs:
# Type 'h' for help
# Type 'r' to read ADC once  
# Type 's' to start streaming
# Type 'q' to stop streaming

Troubleshooting

No Serial Output

1. Check connections:

   • PA0 (TX) → Serial adapter RX
   • PA1 (RX) → Serial adapter TX
   • GND → GND

2. Verify settings:

   • Baud rate: 9600
   • Data bits: 8
   • Parity: None
   • Stop bits: 1

3. Test adapter:

   • Try different USB-to-Serial adapter
   • Check adapter drivers

LED Not Working

1. Check PB5 connection
2. Verify LED polarity
3. Use appropriate current-limiting resistor (330Ω)

ADC Issues

1. Input range: Ensure 0-3.3V on PA2
2. Reference: ADC uses VDD as reference
3. Test with known voltage (e.g., 1.5V battery)

Next Steps

Once you have serial communication working:

1. Explore USART Peripheral documentation
2. Learn ADC Configuration details
3. Try Custom Applications using serial
4. Check Troubleshooting for advanced issues

Related Documentation

• USART2 Configuration Guide
• Serial Troubleshooting
• PY32F003 Device Guide
• DFN8 Package Guide