SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The return-to-one mechanism on the HDQ/1-Wire bus is a simple pull-up resistor. Consequently, an excessive wire load of the HDQ/1-Wire bus can cause a significant delay to the bus rise time. This can prevent the module state machine from working correctly by reading back an improper value caused by the line delay. To correct such condition by software, it is possible to configure the HDQ_CTRL_STATUS[10:8] BITFSM register bitfield with the expected line delay. This way the module state machine waits the proper time interval, before reading back the line value. The delay can be adjusted in 1.33 µs steps. The default value of BITFSM = 0x0 corresponds to 1.33 µs delay.
Bus delay can be calculated as follows: Tdelay ≈ 2.2 × Rpullup × Cline
See more information in the Device Data Manual.