9504 Solar Charge Controller

Production Firmware v1.0 - User Guide

1. System Overview

The 9504 Solar Charge Controller is a comprehensive monitoring and control system designed for solar panel arrays. The production firmware provides real-time monitoring of solar panel voltages, temperature sensing, current monitoring, and LED control capabilities.

2. Hardware Configuration

Pin Assignments

Component	Pins	Function
Shift Register 1	D2, D3, D4	LED Control (A, B, C)
Shift Register 2	D5, D6, D7	Solar Voltage Sensing (A, B, C)
Shift Register 3	D8, D9, D10	Temperature Sensing (A, B, C)
Temperature Excitation	D20	Thermistor Bias Control
Analog Inputs	A0, A1, A2	Temperature, Solar Voltage, LED Output
I2C Bus	A4, A5	INA219 Current Monitor

LED Configuration

3. Communication Setup

Input Modes

The system supports two input modes for maximum flexibility:

Terminal Mode (Default)

• Character-by-character input with echo
• Backspace support for editing
• Enter key terminates commands
• Interactive terminal experience

String Mode

• Full string input without echo
• Multiple commands per string
• Terminated by newline, semicolon, or null
• Ideal for automated systems

4. Command Reference

System Commands

Command	Description	Example
help	Display all available commands	help
status	Show current system status	status
info	Display system information	info
reset	Perform system reset	reset
test	Run comprehensive system test	test

LED Control Commands

Command	Description	Example
led <n> on [brightness]	Turn on LED n (0-7) with optional brightness (0-100)	led 0 on 75
led <n> off	Turn off LED n	led 0 off
led <n> blink [rate]	Set LED n to blink with optional rate (ms)	led 6 blink 1000

Configuration Commands

Command	Description	Example
config mode <value>	Set system mode (1=normal)	config mode 1
watchdog on/off	Enable/disable watchdog timer	watchdog off
terminal	Switch to terminal input mode	terminal
string	Switch to string input mode	string
mode	Show current input mode	mode
limits	Show sensor filtering limits	limits

5. LED Control System

LED Modes

• OFF: LED is completely off
• ON: LED is on at specified brightness (0-100%)
• BLINK: LED blinks at specified rate (default 500ms)
• FADE: LED fades smoothly (future enhancement)

Default LED Behavior

• LED 6: Heartbeat indicator (blinks every second)
• LED 7: System active indicator (solid on at 50% brightness)
• LEDs 0-5: User controllable side LEDs

LED Control Examples

6. Data Packet Format

The system transmits structured data packets every 5 seconds in the following format:

Packet Type 1: Solar Voltages

Field	Description	Range
$SCC	Packet identifier	Fixed
1	Packet type	Fixed
1.0,1.2,1.5,1.2,1.2,1.5	Solar panel voltages (6 panels)	0.0-5.0V
*	Packet terminator	Fixed

Packet Type 2: Temperature Readings

Field	Description	Range
$SCC	Packet identifier	Fixed
2	Packet type	Fixed
23.5,23.5,23.5,23.5,23.5,23.5,23.5,23.5	Temperature readings (8 channels)	-20.0 to +40.0°C
*	Packet terminator	Fixed

Packet Type 3: Output Monitoring and Status

Field	Description	Range
$SCC	Packet identifier	Fixed
3	Packet type	Fixed
12.34	Output voltage (INA219)	0.0-5.0V
150.5	Output current (mA)	Unlimited
1	System mode	1=Normal
*	Packet terminator	Fixed

7. Sensor Monitoring

Solar Panel Voltage Monitoring

• Channels: 6 individual solar panels
• Range: 0.0V to 5.0V (filtered)
• Update Rate: Every loop cycle (~10ms)
• Filtering: Out-of-range values default to 0.0V

Current and Voltage Monitoring (INA219)

• Shunt Resistor: 0.33 ohm
• Voltage Range: 0.0V to 5.0V (filtered)
• Current Range: Unlimited (can be negative for discharge)
• Calibration: 32V, 2A range for optimal resolution

Temperature Monitoring

• Channels: 8 temperature sensors
• Sensor Type: 10k ohm thermistors
• Range: -20.0°C to +40.0°C (filtered)
• Excitation: 5V through 10k resistor
• Conversion: B25/85 = 3950K approximation

8. Troubleshooting

Common Issues

No Response to Commands

• Check baud rate (9600 bps)
• Verify serial connection
• Try sending 'help' command
• Check input mode with 'mode' command

LEDs Not Working

• Run 'test' command to verify LED hardware
• Check LED number (0-7)
• Verify command syntax: 'led 0 on 50'
• Check if LED is in correct mode

Sensor Readings at 0.0

• Check sensor connections
• Verify shift register addressing
• Run 'test' command for sensor verification
• Check 'limits' command for filtering status

System Resets Frequently

• Check watchdog status with 'status' command
• Disable watchdog temporarily: 'watchdog off'
• Check power supply stability
• Verify no short circuits

9. Technical Specifications