ST78C34 Exar Corporation, ST78C34 Datasheet

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... I/O port. It contains all the necessary input/output signals to be configured as a CENTRONICS printer port. The ST78C34 is a general purpose input/output con- troller with 83 byte internal FIFO. FIFO operation can be enabled or disabled. For CENTRONICS printer operation, all registers are mapped to IBM printer port registers ...

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... ST78C34 Figure 1, PACKAGE DESCRIPTION, ST78C34 Plastic-DIP Package -ERROR 1 SLCT 2 BUSY 3 -ACK INTSEL N.C. 15 INT 16 XTAL1 17 XTAL2 18 -CS 19 GND 20 Rev. 3.00 40 VCC 39 -IOR 38 -IOW N.C. 34 PD7 33 PD6 32 PD5 31 PD4 30 PD3 29 PD2 28 PD1 ...

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... Figure 2, BLOCK DIAGRAM D0-D7 -IOR -IOW RESET A0-A1 -CS INT INTSEL Rev. 3.00 ST78C34 Printer Printer FIFO Data Registers Ports Printer Control Logic Clock & Timing Generator 6-5 PD0-PD7 -STROBE INIT -AUTOFDX -SELCTIN PE, SELECT BUSY, -ACK -ERROR XTAL2 XTAL1 ...

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... XTAL2 pin to utilize the internal oscillator circuit. An external clock can be used to clock oscillator circuit. O Crystal input 2 or buffered clock output. See XTAL1. I Chip select (active low). A low at this pin enables the ST78C34 / CPU data transfer operation. 6-6 Pin Description ...

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... To select the line printer. O Power and signal ground. I/O Bi-directional parallel ports (three state). To transfer data in or out of the ST78C34 parallel port. PD7-PD0 are latched during output mode. I Address lines. To select internal registers. I Write strobe (active low). A low on this pin will transfer the contents of the CPU data bus to the addressed register ...

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... Alternate Func- tion Register bit 0-2 are used to control the delay and width of -STROBE. Handshaking between the printer and the ST78C34 may be controlled by bit-3 of the Alternate Function Register. Setting this bit to a “1” will result in the use of BUSY instead of -ACK for FIFO reading and interrupt control. INT will transition low when a “ ...

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... The polarity of the INT pin may be inverted by setting Alternate Function Register bit-6 high. The ST78C34 provides additional programmable in- terrupt output options by programming the Alternate Function Register bit 4-5. INT output can be selected as FIFO full or FIFO empty interrupt. ...

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... ST78C34 COM BIT-2: INIT input pin. 0= INIT pin is in low state 1= INIT pin is in high state COM BIT-3: -SLCTIN input pin. 0= -SLCTIN pin is in high state 1= -SLCTIN pin is in low state COM BIT-4: Interrupt mask. 0= Interrupt (INT output) is disabled 1= Interrupt (INT output) is enabled COM BIT 7-5: Not used. Are set to “ ...

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... FIFO byte count. Number of characters left in FIFO. FCRB bit-0 is the LSB bit of the counter and FCRB bit the MSB bit of the counter. FBCR BIT-7: FIFO state. 0= FIFO is enabled 1= FIFO is disabled Rev. 3.00 ST78C34 EXTERNAL RESET CONDITION STR bit-6 SIGNALS 1 -ACK PD0-PD7 1 ...

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... ST78C34 ST78C34 REGISTER CONFIGURATIONS A1 A0 REGISTER PD7 0 1 STR BUSY/ -FIFO full 1 0 COM CON AFR FIFO enable 1 1 FBCR -FIFO status Rev. 3. PD6 PD5 PD4 PD3 None PE SLCT ERROR Latched INT 1 1 INT -SLCTIN ...

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... Delay from -IOR to data 26 T -ACK pulse width 39 T PD7 - PD0 setup time 40 T PD7 - PD0 hold time 41 T Delay from -ACK low to interrupt low 42 T Delay from -IOR to reset interrupt 43 Rev. 3.00 ST78C34 Limits Units Min Typ Max ...

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... ST78C34 ABSOLUTE MAXIMUM RATINGS Supply range Voltage at any pin Operating temperature Storage temperature Package dissipation DC ELECTRICAL CHARACTERISTICS T =0° - 70° C, Vcc=5.0 V ± 10% unless otherwise specified. A Symbol Parameter V Clock input low level ILCK V Clock input high level IHCK V Input low level IL V Input high level ...

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... A0-A2 T8 -CS T21 -IOR T26 D0-D7 A0-A2 T8 -CS T14 -IOW D0-D7 Rev. 3.00 Valid Address T9 Active T23 T24 Active T19 Data General read timing Valid Address T9 Active T15 T16 Active T12 T13 Data General write timing 6-15 ST78C34 T25 Active Data 7834-RD-1 T17 Active Data 7834-WD-1 ...

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... ST78C34 -ACK T40 -INT -IOR T40 NORMAL MODE INTSEL PD0-PD7 T2 EXTERNAL CLOCK Rev. 3.00 T39 Active Active Active INTERRUPT LATCHED MODE SELECT T41 VALID DATA Interrupt timing T1 T3 External clock timing 6-16 Active T42 Active T43 Active 7834-PR-1 7834-CK-1 ...

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... RESET INIT -STROBE 0-2 CLOCK FIFO RESET DO-D7 -IOW -IOR PDO-PD7 Rev. 3.00 INIT LOW FORCES -STROBE HIGH 1-2 CLOCK Data Active Printer special mode 6-17 ST78C34 0-2 CLOCK Data Data Active Active Data 16553-PW-1 ...

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... ST78C34 RESET Active D0-D7 PD0-PD7 Active -IOW -STROBE -ACK ` FIFO EMPTY Rev. 3.00 Active DATA-1 DATA-2 Active Active Active Active FIFO EMPTY FIFO mode entered after first -STROBE and -ACK -STROBE generated internally -INTP generated internally Printer auto FIFO mode 6-18 Active Active DATA-3 ...

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... BUSY SELECTED FOR FIFO OPERATION BUSY 2-4 CLOCK FIFO READ (INTERNAL) 5-10 CLOCKS PD OUTPUT PORTS -STROBE Printer FIFO timing with more than one byte in the FIFO Rev. 3.00 Active 0-2 CLOCK Active 3-6 CLOCKS DATA Active DATA 6-19 ST78C34 DATA+1 TSD Active TSW DATA+1 TSD Active TSW 16553-PW-3 ...

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... ST78C34 RESET PD PORT Active Active -IOW PD OUTPUT PORT -STROBE Printer FIFO, with one byte in the FIFO Rev. 3.00 Active Active Active Active TSD TSW 6-20 16553-PW-4 ...

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LEAD PLASTIC DUAL-IN-LINE Seating Plane L B Note: The control dimension is the inch column Package Dimensions (600 MIL PDIP) Rev. 1. INCHES MILLIMETERS SYMBOL MIN MAX MIN A 0.160 0.250 4.06 ...

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Package Dimensions 44 LEAD PLASTIC LEADED CHIP CARRIER SYMBOL A 0.165 A 0.090 1 A 0.020 2 B 0.013 B 0.026 1 C 0.008 D 0.685 D 0.650 1 ...

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... While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized ...