Energy Meter IC Family Software Instruction Manual

71M652X Software User’s Guide

Revision 1.7 TERIDIAN Proprietary 130 of 138

Timer/Counter Control Register (TCON)

MSB LSB

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

Table 6-47: The TCON Register

Bit Symbol Function

TCON.7 TF1 Timer 1 overflow flag

TCON.6 TR1 Not used for interrupt control

TCON.5 TF0 Timer 0 overflow flag

TCON.4 TR0 Not used for interrupt control

TCON.3 IE1 External interrupt 1 flag

TCON.2 IT1 External interrupt 1 type control bit

TCON.1 IE0 External interrupt 0 flag

TCON.0 IT0 External interrupt 0 type control bit

Table 6-48: The TCON Bit Functions

Interrupt Request Register (IRCON)

MSB LSB

IEX6 IEX5 IEX4 IEX3 IEX2

Table 6-49: The IRCON Register

Bit Symbol Function

IRCON.7 -

IRCON.6 -

IRCON.5 IEX6 External interrupt 6 edge flag

IRCON.4 IEX5 External interrupt 5 edge flag

IRCON.3 IEX4 External interrupt 4 edge flag

IRCON.2 IEX3 External interrupt 3 edge flag

IRCON.1 IEX2 External interrupt 2 edge flag

IRCON.0 -

Table 6-50: The IRCON Bit Functions

Note: Only TF0 and TF1 (timer 0 and timer 1 overflow flag) will be automatically cleared by hardware when the service

routine is called (Signals t0ack and t1ack – port ISR – active high when the service routine is called).

6.3.5.3 External Interrupts

The 71M6521 MPU allows seven external interrupts. These are connected as shown in Table 46. The direction of

interrupts 2 and 3 is programmable in the MPU. Interrupts 2 and 3 should be programmed for falling sensitivity, using

the I2FR and I3FR bits of the T2CON register (see Table 6-50).