NEC PD78214 - Manual (Page 322)

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11
CHAPTER 11 EDGE DETECTION FUNCTION
Pins P20 to P26 support an edge detection function to program a rising or falling edge. The detected edge is sent
to the internal hardware. Table 11-1 shows the relationship between pins P20 to P26, and the use of the detected
edge.
Table 11-1 Pins P20 to P26 and Use of Detected Edge
Pins Use
P20
P21
P22
P23
P24
P25
P26
NMI, control of the standby circuit
INTP0, capture signal of 8-bit timer/counter 1, trigger signal of
real-time output port
INTP1, capture signal of 8-bit timer/counter 2
INTP2, CI (count clock of 8-bit timer/counter 2)
INTP3, capture signal of 16-bit timer/counter
INTP4, ASCK (external baud rate input of UART)
INTP5, conversion start signal of the A/D converter
INTM0
INTM1
Register specifying the edge
to be detected
The edge detection function is always enabled except in STOP mode. (The edge detection function of pin P20 is
enabled even in STOP mode.)
11.1 EXTERNAL INTERRUPT MODE REGISTERS (INTM0, INTM1)
The external interrupt mode registers (INTM0, INTM1) specify the valid edge to be detected on pins P20 to P26.
The INTM0 register specifies the valid edge for pins P20 to P23, while the INTM1 register specifies that for pins P24
to P26.
The INTM1 register can also switch the INTP4 interrupt and INTC30 interrupt (for details see Chapter 12). When
ASCK is input, both edges are detected, independent of the values of these registers.
The 8-bit manipulation instruction and bit manipulation instruction can read and write the contents of the INTM0
and INTM1 registers. Figs. 11-1 and 11-2 show their formats.
When RESET is input, both these registers are set to 00H.