MC68HC705B16CFN Freescale Semiconductor, MC68HC705B16CFN Datasheet - Page 113
Manufacturer Part Number
IC MCU 2.1MHZ 15K OTP 52-PLCC
Specifications of MC68HC705B16CFN
Number Of I /o
Program Memory Size
15KB (15K x 8)
Program Memory Type
256 x 8
352 x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
-40°C ~ 85°C
Package / Case
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
INTP, INTN — External interrupt sensitivity options
These two bits allow the user to select which edge the IRQ pin is sensitive to as shown in
external reset. Therefore the device is initialised with negative edge and low level sensitivity.
INTE — External interrupt enable
The INTE bit can be written to only while the I-bit is set, and is set by power-on or external reset,
thus enabling the external interrupt function.
to re-emphasize here that in order to avoid any conflict and spurious interrupt, it is only possible
to change the external interrupt options while the I-bit is set. Any attempt to change the external
interrupt option while the I-bit is clear will be unsuccessful. If an external interrupt is pending, it will
automatically be cleared when selecting a different interrupt option.
9-3. Both bits can be written to only while the I-bit is set, and are cleared by power-on or
0 (clear) –
describes the various triggering options available for the IRQ pin, however it is important
The bits shown shaded in the above representation are explained individually in the
relevant sections of this manual. The complete register plus an explanation of each bit
can be found in
If the external interrupt function is disabled by the INTE bit and an external interrupt is
sensed by the edge detector circuitry, then the interrupt request is latched and the
interrupt stays pending until the INTE bit is set. The internal latch of the external
interrupt is cleared in the first part of the service routine (except for the low level
External interrupt function (IRQ) enabled.
External interrupt function (IRQ) disabled.
RESETS AND INTERRUPTS
Table 9-3 IRQ sensitivity
Negative edge and low level sensitive
Negative edge only
Positive edge only
Positive and negative edge sensitive
WDOG ?001 000?