SFFS700 May 2024 TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
Hardware redundancy techniques can be applied via hardware or as a combination of hardware and software to provide runtime diagnostic. In this implementation, redundant hardware resources are utilized to provide diagnostic coverage for elements within and outside (wiring harness, connectors, transceiver) TMS320F28P65xD/S MCU.
In case of peripherals like GPIO, XBAR, PWM, OTTO (HRPWM), DAC, CMPSS, XINT, hardware redundancy can be implemented by having multichannel parallel outputs (where independent outputs are used for transmitting information, and failure detection is carried out via internal or external comparators) or input comparison/voting (comparison of independent inputs to ensure compliance with a defined tolerance range (time, value)). In such scenarios, the system can be designed such that the failure of one input/output does not cause the system to go into a dangerous state. While servicing the error conditions (redundancy conditions) as in two redundant sources tripping the PWM, always read-back the status flags and ensure that both sources are active while tripping and thus providing latent fault coverage for the trip logic.
In case of peripherals like SDFM, ADC, ECAP, EQEP and so forth, hardware redundancy may be implemented by having multiple instance of the peripheral sample the same input and simultaneously perform the same operation followed by cross check of the output values. The ADC on this device has a built-in hardware-based error checker for doing this comparison. See Hardware Redundancy with ADC Safety Checker for more details.
In case of communication peripherals like DCAN, SPI, SCI and so forth hardware redundancy during signal reception can be implemented by having multiple instance of the peripheral receive the same data followed by comparison to ensure data integrity. Hardware redundancy during transmission can be employed by having complete redundant signal path (wiring harness, connectors, transceiver) from the transmitter to receiver or by sampling the transmitted data by a redundant peripheral instance followed by data integrity check.
While implementing hardware redundancy for ADC and DAC modules, additional care needs to be taken to ensure common cause failures do not impact both instances in same way. Reference voltage sources configured for redundant module instances should be independent. Additionally for ADC SOC trigger sources used for redundant ADC instance should be configured to different PWM module instance. In case of DAC module the comparator can be implemented using an external device.
While implementing hardware redundancy for GPIO module, it is recommended to use nonadjacent GPIO pins from different GPIO groups to avoid common cause failures.