H8SXSLASH1663 datasheet(608/1158 Pages) RENESAS

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Section 10 16-Bit Timer Pulse Unit (TPU)

Rev.1.00 Jun. 07, 2006 Page 556 of 1102

REJ09B0294-0100

10.4.6

Phase Counting Mode

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

TCNT is incremented/decremented accordingly. This mode 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 10.32 shows the correspondence between external clock pins and channels.

Table 10.32 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

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