Working on branching to a PlatformIO implementation

HELPStat/Software/.gitignore

@@ -0,0 +1,9 @@
+# PlatformIO
+.pio/
+.pioenvs/
+.piolibdeps/
+
+# IDE
+.vscode/
+!.vscode/extensions.json
+.idea/

HELPStat/Software/AD594x_EIS_Demo/AD594x_EIS_Demo.ino → HELPStat/Software/AD594x_EIS_Demo/AD594x_EIS_Demo.cpp

@@ -29,10 +29,17 @@
     SOFTWARE.
 */
 
+#include <Arduino.h>
 #include "HELPStat.h"
 #include <vector>
 #include <string>
 
+/* Forward declarations.
+   Unlike an .ino sketch (where the Arduino build auto-generates prototypes), a
+   .cpp must declare any function used before it is defined. blinkLED() is called
+   in loop() but defined at the bottom of the file. */
+void blinkLED(int cycles, bool state);
+
 /* Reference constants for gain values - taken from AD5941.h library by Analog Devices */
 //#define HSTIARTIA_200               0     /**< HSTIA Internal RTIA resistor 200  */
 //#define HSTIARTIA_1K                1     /**< HSTIA Internal RTIA resistor 1K   */

HELPStat/Software/README.md

@@ -0,0 +1,68 @@
+# HELPStat Firmware (PlatformIO)
+
+Firmware for the HELPStat potentiostat — an **Adafruit ESP32-S3 Feather** driving
+an Analog Devices AD5941 for electrochemical impedance spectroscopy (EIS), with
+BLE control, SD logging, and on-device Levenberg–Marquardt Randles-cell fitting.
+
+Originally an Arduino IDE sketch; this directory is now a self-contained
+PlatformIO project. The sketch has been converted to a standard C++ translation
+unit (`AD594x_EIS_Demo.cpp`) for clean PlatformIO compilation.
+
+## Layout
+
+| Path | Purpose |
+|------|---------|
+| [platformio.ini](platformio.ini) | PlatformIO build configuration |
+| [AD594x_EIS_Demo/AD594x_EIS_Demo.cpp](AD594x_EIS_Demo/AD594x_EIS_Demo.cpp) | Main program (`src_dir`) |
+| [lib/HELPStatLib/](lib/HELPStatLib/) | AD5941 driver, EIS logic, BLE/SD, LMA fitting |
+| `App/` | Companion Android app (separate Gradle project) |
+
+## Prerequisites
+
+- [PlatformIO Core](https://platformio.org/install) (CLI) or the PlatformIO IDE
+  extension for VS Code.
+- A native terminal. The ESP32 platform installer (pioarduino) **rejects
+  MSYS/MinGW/Git-Bash** — on Windows use **PowerShell** or **cmd**, not Git Bash.
+
+## Build / Upload / Monitor
+
+```sh
+pio run                 # compile (default env: 4MB/2MB-PSRAM Feather)
+pio run -t upload       # flash over USB (auto-resets into the bootloader)
+pio device monitor      # serial monitor @ 115200 (native USB CDC)
+pio run -t upload -t monitor   # flash then monitor
+```
+
+If you have the **8MB no-PSRAM** Feather (Adafruit #5323) instead of the default
+4MB/2MB-PSRAM board (#5477), append `-e adafruit_feather_esp32s3_nopsram` to the
+`run` commands.
+
+In VS Code, use the PlatformIO toolbar (Build / Upload / Monitor) and pick the
+environment from the status bar.
+
+The first build downloads the ESP32 toolchain and the `Eigen-Port` dependency,
+so it takes a few minutes; later builds are fast.
+
+## Configuration notes
+
+- **Platform:** ESP32 Arduino core 3.x via the community
+  [pioarduino](https://github.com/pioarduino/platform-espressif32) fork. The
+  stock PlatformIO `espressif32` platform only ships core 2.x, which this
+  firmware predates.
+- **Board:** Adafruit ESP32-S3 Feather. Two variants are provided as separate
+  environments — `adafruit_feather_esp32s3` (#5477, default) and
+  `adafruit_feather_esp32s3_nopsram` (#5323). These board definitions enable
+  native-USB Serial (`-DARDUINO_USB_CDC_ON_BOOT=1`), so prints appear on the USB
+  serial monitor with no extra wiring. The AD5941/SD pin map lives in
+  [lib/HELPStatLib/constants.h](lib/HELPStatLib/constants.h) and already matches
+  the Feather (SCK 36 / MOSI 35 / MISO 37). Two pins are deliberately reused:
+  GPIO21 (Feather NeoPixel power) for SD chip-select and GPIO7 (STEMMA-QT I2C
+  power) for the optional button — both fine since neither peripheral is used.
+- **Partition:** the board default (1.4 MB app + OTA + UF2). The firmware is
+  ~0.75 MB, so it fits with room to spare and UF2 drag-drop updates still work.
+  SD logging is used for data, not SPIFFS.
+- **Dependency:** `eigen.h` comes from
+  [LinnesLab/Eigen-Port](https://github.com/LinnesLab/Eigen-Port), declared in
+  both `platformio.ini` and `lib/HELPStatLib/library.json`.
+- **`-Wno-error=return-type`** is set so the original sketch — which the Arduino
+  IDE accepted with only a warning — compiles unchanged.

HELPStat/Software/HELPStatLib/constants.h → HELPStat/Software/lib/HELPStatLib/constants.h

@@ -14,22 +14,26 @@
 // #define RESET 21
 // #define ESP32_INTERRUPT 14 // INTERRUPT PIN FOR ESP32
 
-// // ESP32 S3 SPI / RESET / INT PINS
+// Adafruit ESP32-S3 Feather (#5477 / #5323) - SPI / RESET / INT PINS
+// SCK/MOSI/MISO below are the Feather's default hardware SPI pins.
 #define MOSI 35
-#define MISO 37 
+#define MISO 37
 #define SCK 36
-#define CS 11
-#define RESET 10
-#define ESP32_INTERRUPT 9
+#define CS 11               // D11
+#define RESET 10            // D10
+#define ESP32_INTERRUPT 9   // D9
 
 // SD CARD PINS
+// NOTE: on the Feather, GPIO21 is the onboard NeoPixel power pin. It is reused
+// here as the SD chip-select; fine as long as the onboard NeoPixel is unused.
 #define CS_SD 21
 // Need to make sure CLK doesn't exceed SD card maximum
 // Using the same clock is fine for this case
 #define SD_CLK 240000000 / 16
 #define FILENAME "EISdata.csv"
 
-/* USING SCL/SDA PINS AS LED DRIVERS FOR OUTPUT */
+/* Optional button/LED drivers. NOTE: on the Feather, GPIO7 is the STEMMA-QT
+   I2C power pin; reused here, fine as long as STEMMA-QT I2C is unused. */
 #define LED1 6
 #define LED2 7
 

HELPStat/Software/lib/HELPStatLib/library.json

@@ -0,0 +1,19 @@
+{
+  "name": "HELPStat",
+  "version": "1.0.0",
+  "description": "Driver and EIS measurement library for the HELPStat potentiostat (Analog Devices AD5941) on the ESP32, with BLE control, SD logging, and Levenberg-Marquardt Randles-cell fitting.",
+  "keywords": "potentiostat, EIS, AD5941, AD594x, ESP32, impedance, BLE",
+  "authors": [
+    { "name": "Kevin Alessandro Bautista", "email": "kbautis@purdue.edu" },
+    { "name": "Shannon Riegle", "email": "sdriegle@iu.edu" }
+  ],
+  "license": "MIT",
+  "frameworks": "arduino",
+  "platforms": "espressif32",
+  "dependencies": [
+    {
+      "name": "Bolder Flight Systems Eigen",
+      "version": "https://github.com/LinnesLab/Eigen-Port.git"
+    }
+  ]
+}

HELPStat/Software/platformio.ini

@@ -0,0 +1,51 @@
+; PlatformIO project configuration for the HELPStat firmware.
+;
+; Target: Adafruit ESP32-S3 Feather, Arduino framework (core 3.x).
+; The stock PlatformIO `espressif32` platform only ships Arduino core 2.x, so we
+; use the community "pioarduino" fork, which packages Arduino-ESP32 3.x / IDF 5.x.
+;
+; The Feather has no USB-to-UART chip: Serial runs over native USB, which the
+; Adafruit board definitions enable via -DARDUINO_USB_CDC_ON_BOOT=1.
+;
+; Build:    pio run
+; Upload:   pio run -t upload          (auto-resets into the bootloader)
+; Monitor:  pio device monitor         (115200 baud)
+;
+; The default environment is the 4MB/2MB-PSRAM Feather (Adafruit #5477). If you
+; have the 8MB no-PSRAM board (Adafruit #5323), build/upload with:
+;     pio run -e adafruit_feather_esp32s3_nopsram -t upload
+
+[platformio]
+; The sketch folder is used as the source directory; it holds the main program
+; AD594x_EIS_Demo.cpp (converted from the original .ino).
+src_dir = AD594x_EIS_Demo
+default_envs = adafruit_feather_esp32s3
+
+; ---- Settings shared by every environment ----------------------------------
+[env]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip
+framework = arduino
+monitor_speed = 115200
+
+; HELPStatLib (lib/HELPStatLib) is auto-discovered from lib/.
+; Eigen-Port supplies <eigen.h> used by the Levenberg-Marquardt fitting.
+lib_deps =
+    https://github.com/LinnesLab/Eigen-Port.git
+
+build_flags =
+    -DCORE_DEBUG_LEVEL=0
+    -DEIGEN_NO_DEBUG
+    ; The Arduino IDE treats a missing return in a non-void function as a
+    ; warning; the ESP32 platform's build promotes it to an error. Demote it
+    ; back so the original sketch compiles unchanged.
+    -Wno-error=return-type
+
+; ---- Adafruit ESP32-S3 Feather, 4MB Flash / 2MB PSRAM (Adafruit #5477) ------
+; Default board. The sketch's SPI/SD pins (lib/HELPStatLib/constants.h) already
+; match this Feather: SCK 36, MOSI 35, MISO 37.
+[env:adafruit_feather_esp32s3]
+board = adafruit_feather_esp32s3
+
+; ---- Adafruit ESP32-S3 Feather, 8MB Flash / No PSRAM (Adafruit #5323) -------
+[env:adafruit_feather_esp32s3_nopsram]
+board = adafruit_feather_esp32s3_nopsram