A software test can be utilized to test basic functionality of the module and to inject diagnostic errors and check for proper error response. Such a test can be executed at boot or periodically. Software requirements necessary are defined by the software implemented by the system integrator.

Ideas for creating some module specific tests functionality and error tests are shown below:

• SDFM functionality can be checked by sending a known input test sequence to the C2000 MCU, process it using the digital decimation filters and cross check the value against a known value. For detecting faults in comparator interrupt generation logic, a test pattern can be created to configure the high/low threshold register values to min/max values respectively. Interrupt should always be generated with such a configuration.
• DMA functionality can be checked by transferring a known good data from a source memory to the destination memory and checking for data integrity after the transfer. The transfer can be initiated using the software trigger available (CONTROL.PERINTFRC). On chip timer can be used to profile the time required for such a data transfer.
• EMIF functionality can be checked by moving a known good data from an external memory to the internal memory and vice versa and checking for data consistency using CRC or other mechanisms. The test should be repeated for all the masters having access to the external memories. In addition, the test should provide coverage to all the interface pins used for connecting external memory to the C2000 MCU.
• Software test of input and output X-BAR module can be performed by having a loop created (output X-BAR can be used as stimulus to input X-BAR) using the input and output X-BAR, sending a known test sequence at the input and observing it at the final output. Integrity of ePWM X-BAR can be checked by sending the test stimulus and observing the response using ePWM trip or sync functionality.
• Software test of XINT functionality can be checked by configuring the input X-BAR and forcing the corresponding GPIO register to generate an interrupt. The diagnostic coverage can be enhanced by performing checks for the polarity (XINTxCR.POLARITY) and enable (XINTxCR.ENABLE) functionality as well.
• IPC functionality can be checked by using interrupts or polling method by periodically sending test commands and message as defined by software. Timestamping information using the IPCCOUNTERH/L can be embedded along with the message to estimate the delay in communication.
• ECAP and EQEP functionality can be checked by looping back the PWM or GPIO outputs to the respective module inputs, providing a known good sequence as required by the module and observing the module output. In the case of ECAP, the test can be done internally with the help of input X-BAR.
• The PWM module consists of Time-Base (TB), Counter Compare (CC), Action Qualifier (AQ), Dead-Band Generator (DB), PWM Chopper (PC), Trip Zone (TZ), Event Trigger (ET) and Digital Compare (DC) sub-modules. The individual sub-modules can be tested by providing suitable stimulus using PWM and observing the response using one of the capture (timestamping) modules (eCAP, XINT, eQEP, and so forth). It is recommended to cover the various register values associated with application configuration while performing the software test. Due to the regular linear nature of the various sub-modules, it is possible to get high coverage using a software test.
• A software test of SRAM wrapper logic should provide diagnostic coverage for arbitration between various masters having access to the particular SRAM and correct functioning of access protection. This is in addition to the test used to provide coverage of SRAM bit cells (see Section 6.4.3.19).
• The interconnect (INC) functionality can be tested by writing complementary data-patterns like 0xA5A5,0x5A5A, and so forth from processing units viz CPU and CLA, and reading back it from registers of the IPs connected via different bridges. The read-back data can be compared with expected golden values to ensure fault-free interconnect operation. This exercise can be repeated for different data width types of accesses (16/32 bits) and wide address ranges as applicable using both CPU and CLA. The CPU accesses can be repeated for different instances of peripherals used in application connected to various bridges as shown in Figure 4-1.
• DAC has a set of control registers that can be checked by writing complementary data-patterns like 0xA5A5, 0x5A5A, and so forth in 16-bit access mode. All the registers can be read back and compared to expected values. Registers can be checked for reset feature by configuring the registers to 0xA5A5 pattern, asserting soft reset of DAC, reading back the registers and comparing the read back value with the expected reset value. Lock register can be checked to ensure it is set-once. Also, the registers which are getting locked must not update when written. To test core functionality of the DAC module, it can be configured using software to provide a set of predetermined voltage levels. These voltage levels can be measured by external or internal ADC and results thus obtained can be cross checked against the expected value to ensure proper operation. Extreme corner values of DAC as per application can be programmed and tested to check the successful conversion of digital to analog module across a valid range.
• Comparator sub-system (CMPSS) has a set of registers which can be checked by writing complementary data-patterns like 0xA5A5, 0x5A5A, and so forth in both 16- and 32-bit access modes. These can be read back and compared against expected values. These accesses can be covered by applicable masters viz. DMA, CLA and CPU. Features of the CMPSS module such as ramp decrement can be checked for counting down of RAMPDLYA after it is loaded from RAMPDLYS by a rising PWMSYNC signal. It should be ensured that the decrementer reduces to zero and stays there until next reload from RAMPDLYS. Extreme values of RAMPDLYS can be configured before count down. Digital filter CTRIPHFILCTL/CTRIPLFILCTL registers can be checked by configuring them to a variety of N and T values, and then verifying COMPHSTS/COMPLSTS changes with change in filter output. Applicable range of filter clock prescaler values (CTRIPLFILCLKCTL) can be exercised to ensure that filter samples correctly.
• The general operation of the CPU-Timers can be tested by a software test by loading 32-bit counter register TIMH from period register PRDH, starts decrementing of the counter on every clock cycle. When counter reaches zero a timer interrupt output generates an interrupt pulse. While testing the timer functionality vary the Timer Prescale Counter (TPR) value and also vary input clocks by selecting clock source as SYSCLK, INTOSC1, INTOSC2, XTAL, or AUXPLLCLK. Test interrupts generation capability at the end of the timer counting. Check for the time overflow flag and Timer reload (TRB) functions in the TCR register for correct functioning.
• A software test function in DCSM can be implemented independently in zone1, zone2 and unsecured zone to check DCSM functionality. Device security configurations are loaded from OTP to DCSM during the device boot phase. The test function can implement access filtering checks (read-write and execute permissions) to RAMs and flash sectors belonging to the same zone and different zone. An additional check for EXEONLY configuration can also be implemented for the RAMs and flash sectors to ensure that all access other than execute access is blocked.