H8S2245 datasheet(378/818 Pages) RENESAS

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Section 9 16-Bit Timer Pulse Unit (TPU)

Rev.3.00 Mar. 26, 2007 Page 336 of 772

REJ09B0355-0300

9.4.6

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, and 2.

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.

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 9.7 shows the correspondence between external clock pins and channels.

Table 9.7

Phase Counting Mode Clock Input Pins

External Clock Pins

Channels

A-Phase

B-Phase

When channel 1 is set to phase counting mode

TCLKA

TCLKB

When channel 2 is set to phase counting mode

TCLKC

TCLKD

Example of Phase Counting Mode Setting Procedure

Figure 9.25 shows an example of the phase counting mode setting procedure.

Select phase counting mode

Phase counting mode

Start count

[1]

[2]

[1] Select phase counting mode with bits MD3

to MD0 in TMDR.

[2] Set the CST bit in TSTR to 1 to start the

count operation.

Figure 9.25 Example of Phase Counting Mode Setting Procedure

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