Devkit-notes.md

@@ -102,7 +102,7 @@ Enable temperature compensation, setting `0x80` in addition to the existing `0x1
 /usr/sbin/i2cset -y 2 0x1e 0x20 0x98
 ```
 
-Now read the values for each axis (x, y, z respectively):
+Now read the values for each axis (x, y, z respectively) from the 16-bit registers, `OUT_X_[LH]_M`, `OUT_Y_[LH]_M` and `OUT_Z_[LH]_M`:
 ```
 /usr/sbin/i2cget -y 2 0x1e 0x28 w
 /usr/sbin/i2cget -y 2 0x1e 0x2a w
@@ -113,3 +113,40 @@ Set the operating mode to power-down again:
 ```
 /usr/sbin/i2cset -y 2 0x1e 0x22 3
 ```
+
+**Accelerometer and Gyroscope:**
+
+These are not visible to user space programs via `/dev/i2c-2` if the `st_gyro_i2c` module is enabled. With it removed, the `WHO_AM_I_G` register can be read:
+```
+/usr/sbin/i2cget -y 2 0x6a 0x0f
+```
+The output from this should be `0x68`.
+
+The accelerometer can be enabled by setting certain combinations of the top three bits in the `CTRL_REG6_XL` register. Setting the lowest of these three bits causes values to be supplied at a rate of 10 Hz:
+```
+/usr/sbin/i2cset -y 2 0x6a 0x20 0x20
+```
+
+Reading the status from the `STATUS_REG` register indicates whether data is available:
+```
+/usr/sbin/i2cget -y 2 0x6a 0x27
+```
+This may return values with bit 2 set if temperature data is available, and bit 0 set if accelerometer data is available.
+
+If new temperature data is available, it can be read from the 16-bit `OUT_TEMP_[LH]` register:
+```
+/usr/sbin/i2cget -y 2 0x6a 0x15 w
+```
+
+If new accelerometer data is available, it can be read from the 16-bit `OUT_X_XL`, `OUT_Y_XL` and `OUT_Z_XL` registers:
+```
+/usr/sbin/i2cget -y 2 0x6a 0x28 w
+/usr/sbin/i2cget -y 2 0x6a 0x2a w
+/usr/sbin/i2cget -y 2 0x6a 0x2c w
+```
+
+Reset the `CTRL_REG6_XL` register to its original value to disable the accelerometer:
+```
+/usr/sbin/i2cset -y 2 0x6a 0x20 0x0
+```
+The bits in the status register will remain set until any remaining temperature or accelerometer data is read.
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