SH7670 Datasheet, PDF (607/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 15 Stream Interface (STIF)
I. The PWM control variable can directly be set by STPWMR when the PWMSEL bit in
STPWMMR is set to 1. In this case, PWMCYC acts as a number of acceptable comparison
bits as in the case of internal STC value - PCR value (figure 15.9).
15.6.2 PCR Clock Recovery Operation
PCR0
...
PCR1
PCR2
Figure 17.6 TS packet arrival time
to internal PCR bus
...
PCR_PID setting
Input to PCRRCV upon arrival of PCR
PCRRCV
Packet including PCR_PID
(packet with PID set by PCR_PID)
Figure 15.10 Overview of TS Packet
• Example 1: Clock recovery using the PCRRCV hardware
A. Set PWMSEL to 0 to enable the clock recovery using the PCRRCV hardware.
B. Set the PWMCYC, PWMSFT, PWMDIV, and PWMUEN bits in STPWMMR for the
PWM control output.
C. Set the PID bits in STPWMMR to PCR_PID of a packet including PCR for recovering
clock to the PCRRCV. The clock recovery starts upon the PID setting. For this reason, if
the PCR continuity is impaired by a reset or channel change, set PIDEN to 0 and then set a
PID.
D. When a packet including PCR_PID arrives, the PCRRCV extracts the 42-bit
program_clock_reference (PCR) from the adaptation_field of the packet. For packet
conditions for extracting PCR, see table 15.4. When a TS packet that satisfies the
conditions in table 15.4 arrives, a PCR arrival pulse is generated in the PCRRCV.
E. When a PCR arrival pulse is generated, the PCR extracted from the packet is transferred to
the internal PCR register and STC counter. The STC counter (STC) value is also
transferred to the internal STC register at the same time. After that, the STC counter starts
counting by the VCXO clock input. The STC counter value incremented from the previous
PCR until the present time by the VCXO clock is set in the internal STC register, and the
currently arrived PCR is set in the internal PCR register and STC counter.
F. The PWM control variable, which is the comparison result between the internal STC and
PCR registers (STC value - PCR value), is calculated by the PWMCYC, PWMSFT, and
PWMDIV bits in STPWMMR. When the comparison result reflection conditions in table
15.5 are satisfied, the comparison result is reflected in the PWM output control. Setting
Rev. 1.00 Nov. 14, 2007 Page 581 of 1262
REJ09B0437-0100