UPD17P136ACT datasheet(135/292 Pages) NEC

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CHAPTER 13 PERIPHERAL HARDWARE

116

13.1.4 Setting Count Value to Modulo Register

A value is set to the modulo register by using the PUT instruction via DBF (data buffer). The peripheral address

of the modulo register of timer 0 is assigned to 02H, and that of timer 1 is assigned to 03H.

To transfer a value by using the PUT instruction, the data of the low-order 8 bits of DBF (DBF1 and DBF0) are

transferred to the modulo register. Figure 13-4 shows an example of the modulo register of timer 0.

Figure 13-4. Setting Count Value to Modulo Register

Example of setting count value 64H to modulo register of timer 0

CONTDATL

DAT

; Assigns CONTDATL to 4H by using symbol definition instruction

CONTDATH

DAT

; Assigns CONTDATH to 6H by using symbol definition instruction

MOV

DBF0, #CONTDATL ;

MOV

DBF1, #CONTDATH ;

PUT

TM0M, DBF

; Transfers data by using reserved word “TM0M”

8-bit data

PUT TM0M, DBF

TM0M (peripheral address 02H)

DBF3

DBF2

DBF1

DBF0

Don’t care

Data buffer

Caution The range of the value to that can be set to the modulo register is 01H to FFH. If 00H is set, the

normal count operation is not performed.

The modulo register is a write-only register. Therefore, the set value of the modulo register cannot be read. Even

if the “PUT TM0M, DBF” or “PUT TM1M, DBF” instruction is executed while the 8-bit timer/counter is operating, the

count is operating is not stopped.

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