CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS

5.4.2Basic Intercal Timer Mode Register (BTM)

BTM is a 4-bit register which controls the operation of the basic interval timer.

BTM is set by a 4-bit memory handling instruction. Bit operations are not possible.

Example To set the interrupt generation interval to 1.95 ms (4.19 MHz).

MOV

A, #1111B

 

MOV

BTM. A

; BTM 1111B

When bit 3 is set (1), the contents of the basic interval timer are cleared and at the same time the basic interval timer interrupt request flag (IRQBT) is also cleared (start of basic interval timer).

With a RESET input, BTM contents are cleared to zero and the interrupt request signal generation interval is set to the maximum length.

Fig. 5-22 Basic Interval Timer Mode Register Format

Address

F85H

3

2

1

0

BTM3

BTM3

1

1

 

 

 

 

Symbol

BTM

Input Clock Specification

Interrupt Interval

(Wait Time when Standby ) Mode is Released)

0

fXX/29 (8.18 kHz)

217/fXX (31.3 ms)

1

fXX/25 (131 kHz)

213/fXX (19.5 ms)

( ) : Values when fXX = 4.19 MHz

Basic interval timer start control bit

Basic interval timer is started by writeng “1”* (counter and interrupt request flay are interrupt request flag are cleared). Automatically reset (0) when operation is started.

*Ensure that the write is performed by a 4-bit write instruction.

Note Ensure that 1 is written to bits 1 and 0.

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NEC PD75P402, PD75402A user manual Basic Intercal Timer Mode Register BTM, MOV BTM. a, BTM3, Btm