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AT89LV55-12AC Fiches technique(PDF) 4 Page - ATMEL Corporation |
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AT89LV55-12AC Fiches technique(HTML) 4 Page - ATMEL Corporation |
4 / 32 page 4 0811D–MICRO–3/06 AT89LV55 4. Pin Description 4.1 V CC Supply voltage. 4.2 GND Ground. 4.3 Port 0 Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pullups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes dur- ing program verification. External pullups are required during program verification. 4.4 Port 1 Port 1 is an 8-bit bi-directional I/O port with internal pullups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the inter- nal pullups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (I IL) because of the internal pullups. In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the follow- ing table. Port 1 also receives the low-order address bytes during Flash programming and verification. 4.5 Port 2 Port 2 is an 8-bit bi-directional I/O port with internal pullups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the inter- nal pullups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (I IL) because of the internal pullups. Port 2 emits the high-order address byte during fetches from external program memory and dur- ing accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pullups 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. Port 2 also receives the high-order address bits and some control signals during Flash program- ming and verification. Port Pin Alternate Functions P1.0 T2 (external count input to Timer/Counter 2), clock-out P1.1 T2EX (Timer/Counter 2 capture/reload trigger and direction control) |
Numéro de pièce similaire - AT89LV55-12AC |
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Description similaire - AT89LV55-12AC |
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