H8SSLASH2225 datasheet(502/1071 Pages) RENESAS

502 / 1071 page

Section 11 16-Bit Timer Pulse Unit (TPU)

Rev. 5.00 Aug 08, 2006 page 416 of 982

REJ09B0054-0500

11.4.6

Phase Counting Mode

In phase counting mode, the phase difference between two external clock inputs is detected and

TCNT is incremented/decremented accordingly. In the H8S/2227 Group, this mode can be set for

channels 1 and 2. In other groups, it can be set for channels 1, 2, 4, and 5.

When phase counting mode is set, an external clock is selected as the counter input clock and

TCNT operates as an up/down-counter regardless of the setting of bits TPSC2 to TPSC0 and bits

CKEG1 and CKEG0 in TCR. However, the functions of bits CCLR1 and CCLR0 in TCR, and of

TIOR, TIER, and TGR are valid, and input capture/compare match and interrupt functions can be

used.

This can be used for two-phase encoder pulse input.

When overflow occurs while TCNT is counting up, the TCFV flag in TSR is set; when underflow

occurs while TCNT is counting down, the TCFU flag is set.

The TCFD bit in TSR is the count direction flag. Reading the TCFD flag provides an indication of

whether TCNT is counting up or down.

Table 11.31 shows the correspondence between external clock pins and channels.

Table 11.31 Clock Input Pins in Phase Counting Mode

External Clock Pins

Channels

A-Phase

B-Phase

When channel 1 or 5* is set to phase counting mode

TCLKA

TCLKB

When channel 2 or 4* is set to phase counting mode

TCLKC

TCLKD

Note:

* Not available in the H8S/2227 Group.

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