I am developing a simple accelerometer with the MSP-EXP430FR5739. This board is populated with a 3-axis accelerometer: ADXL330. No additional HW is needed.
The MCU program does:
ADC:Samples data from CH_0 to CH_14 in Repeat-Sequence-of-Channels Mode
Sample Rate: ~ 20 Hz/Channel
DMA
UART:HW UART (TX only) with 9600 baud. This 9600 baud is limited by the emulator circuit.
UART TX data1 = ADC_CH_12 = ACC_X; sample "622-X"
UART TX data2 = ADC_CH_13 = ACC_Y; sample "509-Y"
UART TX data3 = ADC_CH_14 = ACC_Z; sample "511-Z"
LEDs: LED_TX and LED_ADC
The PC application does:
Calculate the 3 acceleration components (g_x, g_y, g_z) from the ADC data and the CALIBRATION data
Calculate the magnitude of G; |G| = sqrt(g_x^2 + g_y^2 + g_z^2);
Displays data
CALIBRATION data must be enter by the user once at the beginning. The user has to rotate slowly the board in every 3 direction (and opposite) to find the maximum (+1g) and the minimum (-1g) ADC values of the 3 axis. Enter this 3*2=6 ADC data to the 6 white textboxes. If the CALIBRATION data are correct then |G| must be 1.00 (static acceleration of gravity).
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The TX data can be viewed with putty too:
Requirements:
MSP-EXP430FR5739 board
Code Composer Studio 5.4 to compile the MCU source file:ACC Demo v03_main.c
Windows OS with .Net framework 4 to run the PC app: ACC Demo v03_Release.zip (extract and run "ACC Demo v03.exe").
The CPU usage may be high when PC application receives data. I will try to reduce this in the next version.
