Cypress CY7C638xx ユーザーズマニュアル

Document 38-08035 Rev. *K

Page 37 of 83

Reserved

Int Act Low

TTL Thresh

Reserved

Open Drain

Pull up Enable

Output Enable

–

–

R/W

R/W

–

R/W

R/W

R/W

0

0

0

0

0

0

0

0

These registers control the operation of pins P0.2–P0.4 respectively. The pins are shared between the P0.2–P0.4 GPIOs and 

the INT0–INT2. These registers exist in all enCoRe II parts. The INT0–INT2 interrupts are different from all the other GPIO 

interrupts. These pins are connected directly to the interrupt controller to provide three edge sensitive interrupts with independent 

interrupt vectors. These interrupts occur on a rising edge when Int act Low is clear and on a falling edge when Int act Low is set. 

The pins are enabled as interrupt sources in the interrupt controller registers (

 on page 55 and 

To use these pins as interrupt inputs, configure them as inputs by clearing the corresponding Output Enable. If the INT0–INT2 

pins are configured as outputs with interrupts enabled, firmware can generate an interrupt by writing the appropriate value to the 

P0.2, P0.3 and P0.4 data bits in the P0 Data Register.
Regardless of whether the pins are used as Interrupt or GPIO pins the Int Enable, Int act Low, TTL Threshold, Open Drain, and 

Pull Up Enable bits control the behavior of the pin.
The P0.2/INT0–P0.4/INT2 pins are individually configured with the P02CR (0x07), P03CR (0x08), and P04CR (0x09) respec-

tively.

 Changing the state of the Int Act Low bit can cause an unintentional interrupt to be generated. When configuring these 

interrupt sources, it is best to follow the following procedure:

1. Disable interrupt source
2. Configure interrupt source
3. Clear any pending interrupts from the source
4. Enable interrupt source

TIO Output

Int Enable

Int Act Low

TTL Thresh

Reserved

Open Drain

Pull up Enable

Output Enable

–

R/W

R/W

R/W

–

R/W

R/W

R/W

0

0

0

0

0

0

0

0

These registers control the operation of pins P0.5 through P0.6, respectively. These registers exist in all enCoRe II parts.
P0.5 and P0.6 are shared with TIO0 and TIO1, respectively. To use these pins as Capture Timer inputs, configure them as inputs 

by clearing the corresponding Output Enable. To use TIO0 and TIO1 as Timer outputs, set the TIOx Output and Output Enable 

bits. If these pins are configured as outputs and the TIO Output bit is clear, firmware can control the TIO0 and TIO1 inputs by 

writing the value to the P0.5 and P0.6 data bits in the P0 Data Register.
Regardless of whether either pin is used as a TIO or GPIO pin the Int Enable, Int act Low, TTL Threshold, Open Drain, and Pull 

Up Enable control the behavior of the pin.
TIO0(P0.5) when enabled outputs a positive pulse from the Free Running Timer. This is the same signal that is used internally 

to generate the 1024 

μs timer interrupt. This signal is not gated by the interrupt enable state. The pulse is active for one cycle 

of the capture timer clock.
TIO1(P0.6) when enabled outputs a positive pulse from the programmable interval timer. This is the same signal that is used 

internally to generate the programmable timer interval interrupt. This signal is not gated by the interrupt enable state. The pulse 

is active for one cycle of the interval timer clock.
The P0.5/TIO0 and P0.6/TIO1 pins are individually configured with the P05CR (0x0A) and P06CR (0x0B), respectively.