modem_power.sh

#!/bin/bash
# Toggle SIM7080G HAT power by pulsing the PWRKEY line (BCM GPIO4).
#
# The PWRKEY is wired through an inverting driver:
#   GPIO4 LOW  = key released (module runs)
#   GPIO4 HIGH = key pressed
# A single ~1.5s HIGH pulse = one PWRKEY press, which toggles the module:
# it powers ON if it was off, or OFF if it was on. There is no separate
# "on" / "off" level - the same pulse does both. Check the result with:
#     ./modem_at.py "AT"      (OK = on, no response = off)
#
# Requires `pinctrl` (ships with Raspberry Pi OS). No sudo needed if your user
# is in the `gpio` group (the default `pi`/first user is).
set -e

GPIO=4
PULSE_SECONDS=1.5

echo "Pulsing PWRKEY (GPIO${GPIO}) high for ${PULSE_SECONDS}s to toggle power..."
pinctrl set "$GPIO" op dl      # ensure released (low) to start
sleep 0.3
pinctrl set "$GPIO" dh         # press (high)
sleep "$PULSE_SECONDS"
pinctrl set "$GPIO" dl         # release (low) - and keep it low so it doesn't float

echo "Done. Wait ~15s for the module to boot, then probe with:  ./modem_at.py \"AT\" \"AT\""
echo "NOTE: keep GPIO4 driven low at boot (gpio=4=op,dl in config.txt) or the"
echo "      floating pin will power-cycle the module every ~15s."