gc80c520a CORERIVER Semiconductor, gc80c520a Datasheet - Page 28

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gc80c520a

Manufacturer Part Number
gc80c520a
Description
Midas1.0 Family Mask Rom/eprom/romless 8-bit Turbo Microcontrollers
Manufacturer
CORERIVER Semiconductor
Datasheet
functions will be selected according to the combination of the SFR values.
The drive characteristics of an alternate function are the same with those of general I/O. The logic 0
output pulls a pin low strongly. The logic 1 output changes a pin status with a strong pull-up and
maintains the logic 1 status with a weak pull-up. More than one port pins are assigned to alternate
functions without changing the functions of the other pins.
Note: P1.1/P1.2/P1.3 are assigned to be used as analog input pins (ADC input channel 1/2/3) by the bits
ADC1/ADC2/ADC3 (ADCSEL.1/ADCSEL.2/ADCSEL.3).
6.2.1.3 PORT 2
Port 2 is an 8-bit, bi-directional I/O port with internal pull-up resistors. The pull-up resistors are switched
on/off by the value of the SFR P2SEL. The Port 2 of the devices including internal program memory is
available as a general purpose I/O. Port 2 pins that have 1s written to them float and can be used as
high-impedance inputs. If the internal pull-up resistors are switched on, Port 2 pins are pulled high and
can be used as inputs.
Port 2 emits the high address byte during fetches from external program memory and during accesses to
external data memory that use 16-bit addresses (MOVX @DPTR). It may not be recommended that even
a device including program memory should use its Port 2 as a general purpose I/O port if the device also
accesses external memory. It is because the state of the Port 2 latch will change during any access to
CPU BUS
Alternative Function Output
ADC Block Input
Figure 6-6 Configuration of PORT1
P1.1
SFR
Digital Input
QB
Q
2 OSC
Page 28 of 187
Pulse
ADC1
Pull-
Functional Description
up
P1SEL.1

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