SFFS889 July 2024 TMS320F2800132 , TMS320F2800133 , TMS320F2800135 , TMS320F2800137
The open/shorts detection circuit (OSDETECT) can be used to detect ADC input channel faults in the system. The circuit connects to the ADC input after the channel select multiplexer, but before the S+H circuit, as shown in Figure 6-6. Error response, diagnostic testability, and any necessary software requirements are defined by the software implemented by the system integrator.
The circuit can be operated by writing a value to the DETECTCFG field in the ADCOSDETECT register. This function causes the circuit to source a voltage onto the input during the S+H phase of any conversion. The voltage and drive strength of the OSDETECT circuit for different DETECTCFG settings are given in Table 6-1. For additional details on implementing this diagnostic, see the Opens/Shorts Detection Circuit (OSDETECT) section in the TMS320F280013x Real-Time Microcontrollers Technical Reference Manual.
ADCOSDETECT.DETECTCFG | Source Voltage | S4 | S3 | S2 | S1 | Drive Impedance |
---|---|---|---|---|---|---|
0 | Off | Open | Open | Open | Open | Open |
1 | Zero Scale | Closed | Open | Open | Closed | 5K || 7K |
2 | Full Scale | Open | Closed | Closed | Open | 5K || 7K |
3 | 5/12 VDDA | Open | Closed | Open | Closed | 5K || 7K |
4 | 7/12 VDDA | Closed | Open | Closed | Open | 5K || 7K |
5 | Zero Scale | Open | Open | Open | Closed | 5K |
6 | Full Scale | Open | Open | Closed | Open | 5K |
7 | Zero Scale | Closed | Open | Open | Open | 7K |