GMS90C320 Datasheet, PDF (11/46 Pages) Hynix Semiconductor – HYNIX SEMICONDUCTOR INC. 8-BIT SINGLE-CHIP MICROCONTROLLERS

GMS90C320
Symbol
P2.0-P2.7
PSEN
RESET
ALE
EA
P0.0-P0.7
V_{S S}
V_{C C}
N.C.
Pin Number
P-LCC-44
P-DIP-40
P-MQFP-
44
24-31 21-28 18-25
32
29
26
10
9
4
33
30
27
35
31
29
43-36 39-32 37-30
22
20
16
44
40
38
1,12,
23,34
-
6,17,
28,39
Input/
Output
Function
I/O Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2
pins that have 1s written to them are pulled high by the internal
pull-up resistors and can be used as inputs. As inputs, port 2 pins
that are externally pulled low will source current because of the
pulls-ups (I_IL, in the DC characteristics). 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 pull-ups when emitting 1s. During accesses to external
data memory that use 8-bit addresses (MOVX @Ri), port 2 emits
the contents of the P2 special function register.
O
The Program Store Enable
The read strobe to external program memory when the device is
executing code from the external program memory. PSEN is acti-
vated twice each machine cycle, except that two PSEN activation
are skipped during each access to external data memory. PSEN
is not activated during fetches from internal program memory.
I
RESET
A high level on this pin for two machine cycles while the oscillator
is running resets the device. An internal diffused resistor to V_SS
permits power-on reset using only an external capacitor to V_CC.
O
The Address Latch Enable
Output pulse for latching the low byte of the address during an
access to external memory. In normal operation, ALE is emitted
at a constant rate of 1/6 the oscillator frequency, and can be used
for external timing or clocking. Note that one ALE pulse is skipped
during each access to external data memory.
I
External Access Enable
EA must be external held low to enable the device to fetch code
from external program memory locations 0000_H to FFFF_H. If EA is
held high, the device executes from internal program memory
unless the program counter contains an address greater than its
internal memory size.
I/O Port 0
Port 0 is an 8-bit open-drain bidirectional I/O port. Port 0 pins that
have 1s written to them float and 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 pull-ups when emitting 1s.
Port 0 also outputs the code bytes during program verification in
the GMS97C5x. External pull-up resistors are required during
program verification.
-
Circuit ground potential
-
Supply terminal for all operating modes
-
No connection
OCT. 2000 Ver 1.2
7