arduino: working altsoftserial with WT61 IMU

arduino/.gitignore

@@ -0,0 +1,3 @@
+# arduino test files
+
+test/

arduino/main/imu.cpp

@@ -83,15 +83,11 @@ void imu_init() {
   // Sets WT61 to 9600/20Hz - see IMU.md for command reference
   // Idempotent: if already at 9600, command is garbled and ignored
   imuSerial.begin(115200);
-
-  /* uncomment after I wire up Nano D9 -> WT61 RX*/
-  // imu_send_cmd(0x64);  // 9600 baud / 20Hz
-  // delay(100);          // Let WT61 process and restart
+  imu_send_cmd(0x64);  // 9600 baud / 20Hz
+  delay(100);          // Let WT61 process and restart
 
   // Switch to working baud rate
-  // imuSerial.begin(9600);
-  /* uncomment after I wire up Nano D9 -> WT61 RX*/
-
+  imuSerial.begin(9600);
   rxIndex = 0;
   currentData = {0};
 }

arduino/main/main.ino

@@ -12,17 +12,24 @@ static unsigned long lastTelemetryTime = 0;
 void setup() {
   pinMode(LED_BUILTIN, OUTPUT);
 
+  comms_init();    // Hardware Serial first so we can debug
+  Serial.println(F("[INIT] comms ok"));
+
   voltage_init();
+  Serial.println(F("[INIT] voltage ok"));
+
   imu_init();      // AltSoftSerial on pins 8(RX)/9(TX)
-  comms_init();    // Hardware Serial to Pi at 115200
+  Serial.println(F("[INIT] imu ok"));
 
   // Let IMU warm up a bit before calibrating
   // (WT61 needs a moment to stabilize after power-on)
   delay(500);
 
+  Serial.println(F("[INIT] calibrating..."));
   // Zero calibration - current position becomes reference
   // Blocks for ~250ms while sampling
   imu_calibrate();
+  Serial.println(F("[INIT] calibration done, entering loop"));
 }
 
 void loop() {