R01UH0823EJ0100 Rev.1.00 Page 959 of 1823
Jul 31, 2019
RX23W Group 32. USB 2.0 Host/Function Module (USBc)
32.5.2 Processing When Host Controller is Selected
The following processing is required when operating the USB module as a charging downstream port for battery
charging.
(1) Start driving the VBUS.
(2) Enable the portable device detection circuit.
(3) Monitor the portable device detection signal, and start driving the D– line if the detection signal is high.
(4) Detect when the portable device detection signal is low level and stop driving the D– line.
Or, the following processing can also be used in accordance with the battery charging specification.
(A) After disconnection is detected, start driving the D– line within 200 ms.
(B) After connection is detected, stop driving the D– line within 10 ms.
The D– line must be driven to allow the portable device to detect the primary detection described in
section 32.5.1,
Processing When Function Controller is Selected
. The above steps (1) to (4) apply when the portable device
detection function is provided by hardware. This method is to drive the D– line when the portable device is detected.
Steps (A) and (B) apply when the portable device function is not provided or available by hardware. Regardless of
detection of the portable device, the D– line is driven in the disconnected state and the line is not driven in the connected
state. In the battery charging specification, either of these methods can be used.
For steps (3) and (4), after a change in the portable device detection signal is detected using the PDDETINT interrupt, the
current signal state can be confirmed by reading the PDDETSTS0 flag.
Steps (A) and (B) can be performed only in a software timer.
The following show the process flow for steps (1) to (4) and the process flow for steps (A) to (B), respectively.
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