S912XEG128J2MAA Datasheet, PDF (64/1324 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 1 Device Overview MC9S12XE-Family
1.2.3.13 PE6 / MODB / TAGHI — Port E I/O Pin 6
PE6 is a general-purpose input or output pin. It is used as a MCU operating mode select pin during reset.
The state of this pin is latched to the MODB bit at the rising edge of RESET. This pin is an input with a
pull-down device which is only active when RESET is low. TAGHI is used to tag the high half of the
instruction word being read into the instruction queue.
The input voltage threshold for PE6 can be configured to reduced levels, to allow data from an external
3.3-V peripheral to be read by the MCU operating at 5.0 V. The input voltage threshold for PE6 is
configured to reduced levels out of reset in expanded and emulation modes.
1.2.3.14 PE5 / MODA / TAGLO / RE — Port E I/O Pin 5
PE5 is a general-purpose input or output pin. It is used as an MCU operating mode select pin during reset.
The state of this pin is latched to the MODA bit at the rising edge of RESET. This pin is shared with the
read enable RE output. This pin is an input with a pull-down device which is only active when RESET is
low. TAGLO is used to tag the low half of the instruction word being read into the instruction queue.
The input voltage threshold for PE5 can be configured to reduced levels, to allow data from an external
3.3-V peripheral to be read by the MCU operating at 5.0 V. The input voltage threshold for PE5 is
configured to reduced levels out of reset in expanded and emulation modes.
1.2.3.15 PE4 / ECLK — Port E I/O Pin 4
PE4 is a general-purpose input or output pin. It can be configured to drive the internal bus clock ECLK.
ECLK can be used as a timing reference. The ECLK output has a programmable prescaler.
1.2.3.16 PE3 / LSTRB / LDS / EROMCTL— Port E I/O Pin 3
PE3 is a general-purpose input or output pin. In MCU expanded modes of operation, LSTRB or LDS can
be used for the low byte strobe function to indicate the type of bus access. At the rising edge of RESET
the state of this pin is latched to the EROMON bit.
1.2.3.17 PE2 / R/W / WE— Port E I/O Pin 2
PE2 is a general-purpose input or output pin. In MCU expanded modes of operations, this pin drives the
read/write output signal or write enable output signal for the external bus. It indicates the direction of data
on the external bus.
1.2.3.18 PE1 / IRQ — Port E Input Pin 1
PE1 is a general-purpose input pin and the maskable interrupt request input that provides a means of
applying asynchronous interrupt requests. This will wake up the MCU from stop or wait mode.
1.2.3.19 PE0 / XIRQ — Port E Input Pin 0
PE0 is a general-purpose input pin and the non-maskable interrupt request input that provides a means of
applying asynchronous interrupt requests. This will wake up the MCU from stop or wait mode. The XIRQ
MC9S12XE-Family Reference Manual Rev. 1.25
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Freescale Semiconductor