 |
数据搜索系统，热门电子元器件搜索 |
|
|
数据搜索系统，热门电子元器件搜索 |
|
PIC16F676-I/P 数据表(PDF) 21 Page - Microchip Technology |
|
|
|||||||||||||||||||||||||||||
PIC16F676-I/P 数据表(HTML) 21 Page - Microchip Technology |
|
|
21 / 132 page  2010 Microchip Technology Inc. DS40039F-page 21 PIC16F630/676 3.0 PORTS A AND C There are as many as twelve general purpose I/O pins available. Depending on which peripherals are enabled, some or all of the pins may not be available as general purpose I/O. In general, when a peripheral is enabled, the associated pin may not be used as a general purpose I/O pin. 3.1 PORTA and the TRISA Registers PORTA is an 6-bit wide, bidirectional port. The corre- sponding data direction register is TRISA. Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., put the contents of the output latch on the selected pin). The exception is RA3, which is input only and its TRIS bit will always read as ‘1’. Example 3-1 shows how to initialize PORTA. Reading the PORTA register reads the status of the pins, whereas writing to it will write to the PORT latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the PORT data latch. RA3 reads ‘0’ when MCLREN = 1. The TRISA register controls the direction of the PORTA pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISA register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. EXAMPLE 3-1: INITIALIZING PORTA 3.2 Additional Pin Functions Every PORTA pin on the PIC16F630/676 has an interrupt-on-change option and every PORTA pin, except RA3, has a weak pull-up option. The next two sections describe these functions. 3.2.1 WEAK PULL-UP Each of the PORTA pins, except RA3, has an individu- ally configurable weak internal pull-up. Control bits WPUAx enable or disable each pull-up. Refer to Register 3-3. Each weak pull-up is automatically turned off when the port pin is configured as an output. The pull-ups are disabled on a Power-on Reset by the RAPU bit (OPTION<7>). REGISTER 3-1: PORTA — PORTA REGISTER (ADDRESS: 05h) Note: Additional information on I/O ports may be found in the PIC® Mid-Range Reference Manual, (DS33023) Note: The ANSEL (91h) and CMCON (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. The ANSEL register is defined for the PIC16F676. BCF STATUS,RP0 ;Bank 0 CLRF PORTA ;Init PORTA MOVLW 05h ;Set RA<2:0> to MOVWF CMCON ;digital I/O BSF STATUS,RP0 ;Bank 1 CLRF ANSEL ;digital I/O MOVLW 0Ch ;Set RA<3:2> as inputs MOVWF TRISA ;and set RA<5:4,1:0> ;as outputs BCF STATUS,RP0 ;Bank 0 U-0 U-0 R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x — — RA5 RA4 RA3 RA2 RA1 RA0 bit 7 bit 0 bit 7-6: Unimplemented: Read as ‘0’ bit 5-0: PORTA<5:0>: PORTA I/O pin bits 1 = Port pin is >VIH 0 = Port pin is <VIL Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown |
|
链接网址 |
| ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 数据表链接 | 链接交换 | 制造商名单 All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
