Teensy: Add I2C

Author: Joe7M

src/platform/teensy/samples/i2c_bh1750.bas

@@ -0,0 +1,28 @@
+import teensy
+
+const ADDRESS = 0x23
+
+Print "Open I2C"
+const I2C = teensy.OpenI2C(1)   ' use I2C pins 16 and 17
+Print "Opened"
+
+' Power down
+I2C.Write(ADDRESS, 0x00)
+' Power on
+I2C.Write(ADDRESS, 0x01)
+delay(500)
+
+' Send "Continuously H-resolution mode" instruction
+I2C.write(ADDRESS, 0b00010000)
+delay(200)
+
+while(1)
+  ' Read H-resolution measurement result
+  d = I2C.read(ADDRESS, 2)
+  ValueHighRes = ((d[0] lshift 8) BOR d[1]) / 1.2
+
+  ii++  
+  print ii, "High resolution: " + valueHighRes + " lx"
+
+  delay(500)
+wend

src/platform/teensy/samples/i2c_bmp180.bas

@@ -0,0 +1,116 @@
+import teensy
+
+const ADDRESS = 0x77
+const Oversampling = 0
+
+I2C = teensy.OpenI2C(1)   ' use I2C pins 16 and 17
+I2C.setClock(100000)
+Init()
+
+while(1)
+  ii++
+  m = StartMeasurement()
+  print ii, m[0]; "°C", m[1]/100; "hPa" 
+  delay(500)
+wend
+
+sub Init()
+  local buffer
+  ' Get chip id
+  I2C.write(ADDRESS, 0xD0)
+  buffer = I2C.read(ADDRESS, 1)
+  if(buffer != 85)
+    print "Error Chip ID does not match"
+    while(1)
+    wend
+  endif
+
+  ' Read calibration values
+  ac1 = short(Read_2Bytes(0xAA))
+  ac2 = short(Read_2Bytes(0xAC))
+  ac3 = short(Read_2Bytes(0xAE))
+  ac4 = Read_2Bytes(0xB0)
+  ac5 = Read_2Bytes(0xB2)
+  ac6 = Read_2Bytes(0xB4)
+  b1  = short(Read_2Bytes(0xB6))
+  b2  = short(Read_2Bytes(0xB8))
+  mb  = short(Read_2Bytes(0xBA))
+  mc  = short(Read_2Bytes(0xBC))
+  md  = short(Read_2Bytes(0xBE))
+end
+
+func short(dat)
+    if dat > 32767 then
+        return dat - 65536
+    else
+        return dat
+    endif
+end
+
+func StartMeasurement()
+
+  local buffer, UncompTemp, Temperature, UncompPres, Pressure
+  local x1, x2, x3, b3, b5, b6, b4, b7
+
+  ' Read uncompensated temperature
+  buffer = [0xF4, 0x2E]
+  I2C.write(ADDRESS, buffer)
+  delay(5)
+  buffer[0] = Read_Byte(0xF6)
+  buffer[1] = Read_Byte(0xF7)
+  UncompTemp = (buffer[0] lshift 8) BOR buffer[1]
+  
+  ' Read uncompensated pressure
+  buffer[0] = 0xF4
+  buffer[1] = 0x34 + (Oversampling lshift 6)
+  I2C.write(ADDRESS, buffer)
+  delay(2 + (3 lshift Oversampling))
+  I2C.write(ADDRESS, 0xF6)
+  buffer = I2C.read(ADDRESS, 3)
+  UncompPres = ((buffer[0] lshift 16) + (buffer[1] lshift 8) + buffer[0]) rshift (8 - Oversampling)
+
+  ' Calculate true temperature
+  x1 = ((UncompTemp - ac6) * ac5) rshift 15
+  x2 = (mc lshift 11) / (x1 + md)
+  b5 = x1 + x2
+  Temperature = ((b5 + 8) rshift 4) / 10.0
+
+  ' Calculate true pressure
+  b6 = b5 - 4000
+  x1 = (b2 * (b6 * b6) rshift 12) rshift 11
+  x2 = (ac2 * b6) rshift 11
+  x3 = x1 + x2
+  b3 = (((ac1 * 4 + x3) lshift Oversampling) + 2) rshift 2
+  x1 = (ac3 * b6) rshift 13
+  x2 = (b1 * ((b6 * b6) rshift 12)) rshift 16
+  x3 = ((x1 + x2) + 2) rshift 2
+  b4 = (ac4 * (x3 + 32768)) rshift 15
+  b7 = ((UncompPres - b3) * (50000 rshift Oversampling))
+  if (b7 < 0x80000000)
+    Pressure = (b7 lshift 1) / b4
+  else
+    Pressure = (b7 / b4) lshift 1
+  endif
+  x1 = (Pressure rshift 8) * (Pressure rshift 8)
+  x1 = (x1 * 3038) rshift 16
+  x2 = (-7357 * Pressure) rshift 16
+  Pressure = Pressure + ((x1 + x2 + 3791) rshift 4)
+
+  return [Temperature, Pressure]
+end
+
+func Read_2Bytes(Reg)
+  local buffer
+  I2C.write(ADDRESS, Reg)
+  buffer = I2C.read(ADDRESS, 2)
+  temp = (buffer[0] lshift 8) BOR buffer[1]
+  return temp
+end
+
+func Read_Byte(Reg)
+  local buffer
+  I2C.write(ADDRESS, Reg)
+  buffer = I2C.read(ADDRESS, 1)
+  return buffer
+end
+

src/platform/teensy/samples/led.bas

@@ -0,0 +1,11 @@
+import teensy
+
+const BuiltInLED = teensy.openDigitalOutput(13)
+
+while(1)
+  ii++
+  print ii
+  BuiltInLED.write(value)
+  delay(100)
+  value = !value
+wend

src/platform/teensy/src/device.cpp

@@ -17,17 +17,16 @@
 #include "lib/maapi.h"
 #include "serial.h"
 
-#define SERIAL_BAUD_RATE 1000000
-
 //
 // setup the Serial device
+// Teensy 4.x uses USB serial. Setup is done at startup. Communication
+// is always at full USB speed. Either 12 or 480 Mbit/s.
 //
 void serial_init() {
-  Serial.begin(SERIAL_BAUD_RATE);
-  while (!Serial) {
-    // wait
-  }
   if (CrashReport) {
+    while(!Serial) {
+      delay(10);
+    }
     Serial.print(CrashReport);
   }
 }

src/platform/teensy/src/main.cpp

@@ -97,7 +97,12 @@ void serial_read() {
   bool eof = false;
   int lastRead = -1;
 
+  while(!Serial){
+    delay(10);
+  }
+
   dev_print("Waiting for data... ");
+
   buffer.clear();
 
   while (!eof) {

src/platform/teensy/src/module.cpp

@@ -73,3 +73,30 @@ const char *get_param_str(int argc, slib_par_t *params, int n, const char *def)
   }
   return result;
 }
+
+int get_int(var_t *v) {
+  int result;
+  switch (v ? v->type : -1) {
+  case V_INT:
+    result = v->v.i;
+    break;
+  case V_NUM:
+    result = v->v.n;
+    break;
+  default:
+    result = 0;
+    break;
+  }
+  return result;
+}
+
+int get_array_elem_int(var_p_t array, int index) {
+  int result;
+  int size = v_asize(array);
+  if (index >= 0 && index < size) {
+    result = get_int(v_elem(array, index));
+  } else {
+    result = 0;
+  }
+  return result;
+}

src/platform/teensy/src/module.h

@@ -14,6 +14,8 @@ void error(var_p_t var, const char *field, int n);
 void error(var_p_t var, const char *text);
 int get_param_int(int argc, slib_par_t *params, int n, int def);
 const char *get_param_str(int argc, slib_par_t *params, int n, const char *def);
+int get_int(var_t *v);
+int get_array_elem_int(var_p_t array, int index);
 
 typedef struct {
   const char *name;