Hi Martin, As far as the RTOS goes, the code was developed around making sure communication was not preempted as the MSP430F449 can only capture 1 byte at a time (it has no additional buffers or FIFO). Also, every conversion result needs to be captured. In addition there is processing to the display and a check for key presses. So equal priority is to the UART (or the console task) and SPI interface for data capture and display (or the core/analysis tasks). With the least priority to key presses (or the keys task). What you are seeing with the voltage divider has nothing to do with the tasks. The purpose of the voltage divider is to set the common-mode voltage to 2.5V. When jumper J7 is installed, the AINN1 input is connected to 2.5V. If J8 is installed, then the input is shorted so that AINP1 and AINN1 are shorted together at a common-mode of 2.5V. The purpose is for conducting noise measurements tests. When J8 is removed while J7 is still connected, the voltage at AINN1 is still 2.5V, but the input voltage at AINP1 is now floating, but still has a voltage due to the caps on the input. As the caps slowly leak charge the voltage on the cap also reduces slowly. As you have noticed it takes some considerable amount of time for the caps to fully discharge. The operation of the ADS1232REF is fully described in the ADS1232REF user's guide. Your measurement should be ratiometric where the excitation voltage and reference voltage come from the same source. I would suggest that you power your bridge from J4 connector at +5VA and GND. Connect your bridge output to IN1+ and IN1-. An example is shown in the user's guide on page 4 in section 1.4.1. Depending on the range of your output you can set the gain appropriately by using the maximum allowable gain. You can use the GUI software to make device settings or to collect data. You can also control the ADS1232REF via a console terminal assigned to the virtual COM port used by the ADS1232REF . These functions only fully work while the MODE switch is in ANALYSIS mode. SCALE mode and its functionality is designed to be used with the ADS1232REF switches only. Some functionality may work but not all firmware functions are available to both the SCALE and ANALYSIS modes. Best regards, Bob B
↧