A logic analyzer that monitors all 8 exposed GPIO pins on the Flipper Zero 18-pin header, draws live scrolling waveforms on the 128x64 OLED, and logs every sample to a timestamped CSV file on the SD card, with instructions.

Quick start

Grab FAP from Release folder, build and side-load (see Building section below), or download from App Store.
On the Flipper, navigate to Apps > GPIO > GPIO Logic Analyzer.
Select Instructions to review the voltage limits and control map.
Select Start Analyzer to begin capture.
CSV logs are written automatically to /ext/gpio_analyzer/ while capturing.

Screenshots

Screenshots of the various screens can be found here.

Item	Action
Start Analyzer	Opens the live capture screen
Instructions	Four-page on-screen reference guide
About	Version, author, and project URL

Analyzer Screen

GPIO Analyzer         RUN 100Hz*
---------------------------------
A7 [~~~~|__________|~~~~]   H
A6 [_______|~~~~|_______]   L
A4 [____________________]   L
B3 [~~~~~~~~~~~~~~~~~~~~]   H
B2 [____________________]   L
C3 [~~~~|_____|~~~~|____]   L
C1 [_____|~~~~~~~|______]   L
C0 [~~~~~~|______|~~~~~~]   H

Each row is one GPIO pin.
The waveform shows the last 104 samples, scrolling left as new samples arrive.
The newest sample is always the rightmost pixel column.
H / L at the right edge shows the instantaneous pin state.
Vertical lines in the waveform mark state transitions (rising/falling edges).
* after the sample rate in the header means CSV logging is active.

Controls

Button	Action
OK (short)	Toggle capture on / off
OK (long)	Clear waveform history
UP	Increase sample rate
DOWN	Decrease sample rate
BACK	Stop capture, close CSV, exit

Monitored Pins

Row	Label	Pin Name	Header Pin	Notes
1	A7	PA7	Pin 2	3.3V max
2	A6	PA6	Pin 3	3.3V max
3	A4	PA4	Pin 4	5V tolerant
4	B3	PB3	Pin 5	3.3V max
5	B2	PB2	Pin 6	3.3V max
6	C3	PC3	Pin 7	3.3V max
7	C1	PC1	Pin 15	3.3V max
8	C0	PC0	Pin 16	3.3V max

All pins are configured as digital inputs with no internal pull resistor.
They are returned to high-impedance analog mode when you exit the analyzer.

Voltage warning: Do not connect signals above 3.3V to any pin except PA4.
No pull-up or pull-down resistors are enabled. Add external resistors to
your circuit if the signals you are probing have undefined idle states.

FAILURE TO FOLLOW THIS WARNING COULD CAUSE FLIPPER TO LEAK MAGIC SMOKE!

Sample Rates

Rate	Period	Notes
10 Hz	100 ms	Safest for SD write overhead at any card speed
50 Hz	20 ms	Good general-purpose rate
100 Hz	10 ms	Default (balanced speed and reliability)
200 Hz	5 ms	Fast; occasional sample jitter near SD writes
500 Hz	2 ms	Best-effort; may drop samples during CSV flush

Rates are FreeRTOS timer-based. The Flipper OS scheduler and SD write latency can introduce jitter at high rates. For precision timing analysis, use a dedicated logic analyzer. This tool is intended for qualitative signal inspection and basic protocol debugging. YMMV, caveat emptor, all that.

CSV Logging

A new CSV file is created automatically each time you start capture.

Location on SD card:

/ext/gpio_analyzer/gla_YYYYMMDD_HHMMSS.csv

Example: /ext/gpio_analyzer/gla_20240315_143022.csv

File format (comma-separated, CRLF line endings):

sample,A7,A6,A4,B3,B2,C3,C1,C0
0,1,0,1,0,0,1,0,1
1,1,0,1,0,0,1,0,0
2,0,0,1,0,0,1,1,0
...

sample - monotonically incrementing sample number (starts at 0 each session).
Pin columns - 1 = HIGH (3.3V), 0 = LOW (0V).
Column order matches the on-screen row order (A7 top, C0 bottom).
CRLF endings ensure correct display in Excel and LibreOffice Calc.

If the SD card is absent or the directory cannot be created, the app continues without logging (no * in the header) and flashes the error LED.

Building

Assumes repo is cloned to gpio_logic_analyzer and requires ufbt:

pip install ufbt           # install ufbt once
cd gpio_logic_analyzer
ufbt                       # build only (outputs build/.../gpio_logic_analyzer.fap)
ufbt launch                # build and side-load over USB

To build inside the full firmware tree instead:

# Place gpio_logic_analyzer/ under applications_user/
./fbt fap_gpio_logic_analyzer

To change the custom icon, drop a 10x10 pixel PNG named gpio_analyzer_icon.png overwriting the existing.

File Structure

gpio_logic_analyzer/
  application.fam          -- ufbt app manifest
  gpio_analyzer.h          -- shared types, constants, app struct
  gpio_analyzer_app.c      -- entry point, alloc/free, scene handler table
  scene_menu.c             -- main menu (Submenu widget)
  scene_analyzer.c         -- GPIO capture, waveform renderer, CSV logging
  scene_instructions.c     -- 4-page on-screen reference (LEFT/RIGHT to page)
  scene_about.c            -- about screen
  README.md                -- this file

README.md

GPIO Logic Analyzer v2.01 for Flipper Zero