TSC87C52
Pin Description
VSS
Circuit ground potential.
VSS1
Secondary ground (not on DIP). Provided to reduce ground bounce and improve power supply by–passing.
Note: This pin is not a substitute for the VSS pin. Connection is not necessary for proper operation.
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 can sink eight LS TTL inputs.
Port 0 is used as data bus during EPROM programming and program verification.
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, in the DC parameters section) because of the internal pullups.
Port 1 can sink/ source three LS TTL inputs. It can drive CMOS inputs without external pullups.
Port1 also serves the functions of the following special features of the TSC87C52 as listed below:
Port Pin
Alternate Function
P1.0
P1.1
T2 (External Count input to Timer/Counter 2), Clock–Out
T2EX (Timer/Counter 2 Capture/Reload Trigger and direction Control)
Port 1 receives the low–order address byte during EPROM programming and program verification.
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 (IIL, in the DC parameters section) 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.
Port 2 can sink/source three LS TTL inputs. It can drive CMOS inputs without external pullups.
Some Port 2 pins receive the high–order address bits and control signals during EPROM programming and program
verification.
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 (IIL, in the DC parameters section) because of the pullups.
MATRA MHS
Rev. C – 10 Sept 1997
4
Preliminary
TEMIC [ TEMIC SEMICONDUCTORS ]
