Fujitsu FR20 User Manual

265

18.3

Operation of 10-bit General-purpose Prescaler

Division operation of the 10-bit general-purpose prescaler and updating operation of the
reload data latch are described.

■

Division Operation and PO Output

Figure 18.3-1 shows the operation of general-purpose prescaler.

Figure 18.3-1 Operation of general-purpose prescaler

Figure 18.3-2 PO output timing

■

Update Operation of Reload Data Latch

For updating operation of the reload data latch, there are two operation modes, namely updating by

rewriting the data register and updating at both edges of the PPG output. Switch operation mode can be

selected by the LDM bit of the GPRC.

●

Update mode operation by rewriting data register

Under this mode, writing data register executes loading to the reload data latch. Newly loaded data

(division value) is changed to operation with new division value as soon as the division operation using the

previous value ends.

Update of the data register under this mode must be executed at an interval of "2 cycles of the clock

selected by the clock selection bit + 1 machine cycle" or more.

Count value

PO output (Pulse)

PO output (1/2)

Reload Data Latch

0000

CLK

Count value

PO output (Pulse)

PO output (1/2)

002

001

000

XXX

XXX-1

001

000

XXX