reading accel data

lis3dh.py

@@ -6,6 +6,28 @@ import struct
 
 LIS3DH_I2C_ADDR = 0x18
 
+# ODR data rate
+ODR_POWER_OFF = 0b0000
+# all operating modes
+ODR_1_HZ = 0b0001
+ODR_10_HZ = 0b0010
+ODR_25_HZ = 0b0011
+ODR_50_HZ = 0b0100
+ODR_100_HZ = 0b0101
+ODR_200_HZ = 0b0110
+ODR_400_HZ = 0b0111
+# specific operating modes only
+ODR_LP_1600_HZ = 0b1000
+ODR_NORM_1344_HZ = 0b1001
+ODR_LP_5376_HZ = 0b1001
+
+# acc. scale
+FS_2G = 0b00
+FS_4G = 0b01
+FS_8G = 0b10
+FS_16G = 0b11
+
+
 sda_pin = machine.Pin(16) 
 scl_pin = machine.Pin(17)
 
@@ -20,3 +42,54 @@ def write(reg, val):
 # WHO_AM_I
 if read(0x0F, 1)[0] == 0x33:
     print("found LIS3DH")
+
+
+# reboot
+write(0x24, struct.pack("B", 0x80))
+sleep(0.1)
+
+
+Z_en = 1
+Y_en = 1
+X_en = 1
+ctrl_reg1 = 0 | (ODR_10_HZ << 4) | (Z_en << 2) | (Y_en << 1) | X_en
+write(0x20, struct.pack("B", ctrl_reg1))
+
+ctrl_reg4 = 0 | (FS_16G << 4)
+ctrl_reg4 |= 0x80 # set block update
+ctrl_reg4 |= 0x08 # set HR mode
+write(0x23, struct.pack("B", ctrl_reg4))
+
+
+sleep(0.2) # 200 ms
+
+
+while True:
+    
+    while ((read(0x27, 1)[0] >> 3) & 1) == 0:
+        sleep(0.02)
+    
+    data = read(0x28 | 0x80, 6)
+    accX, accY, accZ = struct.unpack("<hhh", data)
+    accX >>= 2
+    accY >>= 2
+    accZ >>= 2
+    
+    # divide depending on FS to get units of mg
+    # this is only for HR mode (maybe)
+    # see table 4 in datasheet
+    
+    # scale output to g
+    #scale = 1/(4 * 1000) # FS_2G HR
+    #scale = 1/(2 * 1000) # FS_4G HR
+    #scale = 1/(1 * 1000) # FS_8G HR
+    scale = 1/(0.3333333 * 1000) # FS_16G HR
+    accX *= scale
+    accY *= scale
+    accZ *= scale
+    
+
+    print(f"x: {accX:.3f}, y: {accY:.3f}, z: {accZ:.3f}")
+
+    
+    sleep(0.05)