Renesas RX Series User Manual

R01UH0823EJ0100 Rev.1.00 Page 954 of 1823
Jul 31, 2019
RX23W Group 32. USB 2.0 Host/Function Module (USBc)
32.3.10 SOF Interpolation Function
When the function controller is selected and if data could not be received at intervals of 1 ms because an SOF packet was
corrupted or missing, the USB interpolates the SOF. The SOF interpolation operation begins when the USBE and SCKE
bits in the SYSCFG register have been set to 1 and an SOF packet is received. The interpolation function is initialized
under the following conditions.
 MCU reset
 USB bus reset
 Suspended state detected
The SOF interpolation operates as follows.
 The interpolation function is not activated until an SOF packet is received.
 After the first SOF packet is received, interpolation is carried out by counting 1 ms with an internal clock of
48 MHz.
 After the second and subsequent SOF packets are received, interpolation is carried out at the previous reception
interval.
 Interpolation is not carried out in the suspended state or while a USB bus reset is being received.
The USB supports the following functions based on the SOF packet reception. These functions also operate normally
with SOF interpolation, if the SOF packet was missing.
 Updating of the frame number
 SOFR interrupt timing
 Isochronous transfer interval count
If an SOF packet is missing, the FRMNUM.FRNM[10:0] flags are not updated.

Renesas RX Series Specifications

General

Brand	Renesas
Model	RX Series
Category	Microcontrollers
Language	English