80C154/83C154
Pin Description
Vss
Circuit Ground Potential.
Port 2
Port 2 is an 8 bit bi-directional I/O port with internal
pullups. Port 2 pins that have 1’s written to them are
pulled high by the internal pullups, and in that state can
be used as inputs. As inputs, Port 2 pins that are externally
being pulled low will source current (ILL, on the data
sheet) because of the internal pullups. Port 2 emits the
high-order address byte during fetches from external
Program Memory and during accesses to external Data
Memory that use 16 bit addresses (MOVX @DPTR). In
this application, it uses strong internal pullups when
emitting 1’s. During accesses to external Data Memory
that use 8 bit addresses (MOVX @Ri), Port 2 emits the
contents of the P2 Special Function Register.
It also receives the high-order address bits and control
signals during program verification in the 83C154. Port
2 can sink or source three LS TTL inputs. It can drive
CMOS inputs without external pullups.
VCC
Supply voltage during normal, Idle, and Power Down
operation.
Port 0
Port 0 is an 8 bit open drain bi-directional I/O port. Port 0
pins that have 1’s written to them float, and in that state
can be used as high-impedance inputs.
Port 0 is also the multiplexed low-order address and data
bus during accesses to external Program and Data
Memory. In this application it uses strong internal pullups
when emitting 1’s. Port 0 also outputs the code bytes
during program verification in the 83C154. External
pullups are required during program verification. Port 0
can sink eight LS TTL inputs.
Port 3
Port 3 is an 8 bit bi-directional I/O port with internal
pullups. Port 3 pins that have 1’s written to them are
pulled high by the internal pullups, and in that state can
be used as inputs. As inputs, Port 3 pins that are externally
being pulled low will source current (ILL, on the data
sheet) because of the pullups. It also serves the functions
of various special features of the TEMIC 51 Family, as
listed below.
Port Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
Port 1
Port 1 is an 8 bit bi-directional I/O port with internal
pullups. Port 1 pins that have 1’s written to them are
pulled high by the internal pullups, and in that state can
be used as inputs. As inputs, Port 1 pins that are externally
being pulled low will source current (IIL, on the data
sheet) because of the internal pullups.
Port 1 also receives the low-order address byte during
program verification. In the 83C154, Port 1 can sink or
source three LS TTL inputs. It can drive CMOS inputs
without external pullups.
2 inputs of PORT 1 are also used for timer/counter 2 :
P1.0 [T2] : External clock input for timer/counter 2. P1.1
[T2EX] : A trigger input for timer/counter 2, to be
reloaded or captured causing the timer/counter 2
interrupt.
Alternate Function
RXD (serial input port)
TXD (serial output port)
INT0 (external interrupt 0)
INT1 (external interrupt 1)
TD (Timer 0 external input)
T1 (Timer 1 external input)
WR (external Data Memory write strobe)
RD (external Data Memory read strobe)
Port 3 can sink or source three LS TTL inputs. It can drive
CMOS inputs without external pullups.
RST
A high level on this for two machine cycles while the
oscillator is running resets the device. An internal
pull-down resistor permits Power-On reset using only a
capacitor connected to VCC. As soon as the result is
applied (Vin), PORT 1, 2 and 3 are tied to 1. This
operation is achieved asynchronously even if the
oscillator is not start up.
4
MATRA MHS
Rev.F (14 Jan. 97)
TEMIC [ TEMIC SEMICONDUCTORS ]
