   else
   if (cmd == 's') servo();
   else
-  if (cmd == 'b') battery();
+  if (cmd == 't') telemetry(); // reply contains a-amps, b-volts, c-charge, u-uptime
   else
   if (cmd == 'i') ina();
   else





// control motors



//=======================================





// telemetry





//=======================================

// telemetry: battery and uptime
void telemetry()
{
  int mV = int(ina219.getBusVoltage_V() * 1000);
  int mA = getAvgAmps();
  Serial.write('b');
  Serial.println(mV);
  Serial.write('a');
  Serial.println(mA);
  Serial.write('c');
  Serial.println(uAh);
  Serial.write('u');
  Serial.println(uptimeSeconds);
}

// INA219 control commands
