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https://github.com/compute-blade-community/compute-blade-agent.git
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03541febb2
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com> Co-authored-by: Cedric Specht <cedric@specht-labs.de>
116 lines
3.7 KiB
Bash
Executable File
116 lines
3.7 KiB
Bash
Executable File
#!/bin/bash
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# find-tach-gpio.sh - Safely probe GPIOs to find fan tachometer signal
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# Run on Radxa node with fan at 100%: sudo ./find-tach-gpio.sh
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#
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# The tachometer generates 2 pulses per revolution. At 5000 RPM:
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# 5000 RPM / 60 = 83.33 RPS * 2 pulses = ~167 Hz
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# At 3000 RPM: ~100 Hz
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# We look for any GPIO showing periodic edge events.
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set -e
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PROBE_DURATION=1 # seconds to monitor each GPIO
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MIN_EVENTS=10 # minimum events to consider "active" (10 events in 1s = 600 RPM minimum)
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DELAY_BETWEEN=0.5 # seconds between probes to let system settle
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# Colors for output
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RED='\033[0;31m'
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GREEN='\033[0;32m'
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YELLOW='\033[1;33m'
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NC='\033[0m' # No Color
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echo "=== Fan Tachometer GPIO Finder ==="
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echo ""
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# Check if running as root (needed for gpiomon)
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if [ "$EUID" -ne 0 ]; then
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echo -e "${RED}Please run as root (sudo)${NC}"
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exit 1
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fi
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# Check fan speed
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FAN_PWM=$(cat /sys/class/hwmon/hwmon8/pwm1 2>/dev/null || echo "unknown")
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echo "Current fan PWM: $FAN_PWM (should be 255 for best detection)"
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if [ "$FAN_PWM" != "255" ]; then
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echo -e "${YELLOW}Setting fan to 100% for detection...${NC}"
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echo 255 > /sys/class/hwmon/hwmon8/pwm1
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sleep 2 # Let fan spin up
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fi
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echo ""
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# Get list of gpiochips
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CHIPS=$(ls /dev/gpiochip* | sed 's|/dev/||')
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echo "Scanning GPIO chips: $CHIPS"
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echo "Probe duration: ${PROBE_DURATION}s per line, minimum ${MIN_EVENTS} events to flag"
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echo ""
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FOUND_CANDIDATES=""
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for chip in $CHIPS; do
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# Get number of lines for this chip
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NUM_LINES=$(gpioinfo $chip 2>/dev/null | wc -l)
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NUM_LINES=$((NUM_LINES - 1)) # Subtract header line
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if [ "$NUM_LINES" -le 0 ]; then
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continue
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fi
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echo -e "${YELLOW}=== Scanning $chip ($NUM_LINES lines) ===${NC}"
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for line in $(seq 0 $((NUM_LINES - 1))); do
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# Check if line is already in use
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LINE_INFO=$(gpioinfo $chip 2>/dev/null | grep "line *$line:" || true)
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if echo "$LINE_INFO" | grep -q "\[used\]"; then
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# Skip lines that are in use
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continue
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fi
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# Probe the line
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printf " Line %2d: " "$line"
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# Run gpiomon with timeout, count events
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EVENTS=$(timeout ${PROBE_DURATION}s gpiomon --num-events=100 $chip $line 2>&1 | wc -l || echo "0")
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if [ "$EVENTS" -ge "$MIN_EVENTS" ]; then
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# Calculate approximate frequency
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FREQ=$((EVENTS / PROBE_DURATION))
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RPM_ESTIMATE=$((FREQ * 60 / 2)) # 2 pulses per revolution
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echo -e "${GREEN}ACTIVE! $EVENTS events (~${FREQ} Hz, ~${RPM_ESTIMATE} RPM)${NC}"
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FOUND_CANDIDATES="$FOUND_CANDIDATES\n $chip line $line: $EVENTS events (~${RPM_ESTIMATE} RPM)"
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elif [ "$EVENTS" -gt 0 ]; then
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echo "$EVENTS events (noise?)"
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else
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echo "no events"
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fi
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# Small delay to let system settle
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sleep $DELAY_BETWEEN
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done
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echo ""
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done
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echo "=== Scan Complete ==="
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if [ -n "$FOUND_CANDIDATES" ]; then
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echo -e "${GREEN}Candidate tachometer GPIOs found:${NC}"
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echo -e "$FOUND_CANDIDATES"
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echo ""
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echo "To verify, try monitoring the candidate with varying fan speeds:"
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echo " gpiomon --num-events=50 <chip> <line>"
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echo ""
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echo "Then add to device tree or HAL configuration."
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else
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echo -e "${YELLOW}No active GPIOs found.${NC}"
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echo "Possible reasons:"
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echo " - Fan tachometer not connected on this carrier board"
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echo " - Tachometer uses a different interface (I2C, ADC, etc.)"
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echo " - Fan doesn't have tachometer wire connected"
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fi
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# Restore fan to auto if we changed it
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if [ "$FAN_PWM" != "255" ] && [ "$FAN_PWM" != "unknown" ]; then
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echo ""
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echo "Restoring fan PWM to $FAN_PWM"
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echo "$FAN_PWM" > /sys/class/hwmon/hwmon8/pwm1
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fi
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