CZ80PIO

CZ80PIO Peripheral Device Megafunction General Description The CZ80PIO, hereinafter referred to as PIO, is a dual-port device which can be programmed by the system software to function as a broad range of peripheral devices that are compatible with the Z80CPU such as most keyboards, printers etc. System design is simplified because the PIO connects directly to the Z80CPU with no additional logic. In larger systems, address decoders and buffers may be required. The CZ80PIO is a microcode-free design developed for reuse in ASIC and FPGA implementations. The design is strictly synchronous, with no internal tri-states and a synchronous reset. Symbol 8 8 data_i data_o data_tri Features ardy astb_n 8 8 8 • • • Provides a direct interface between Z80 microprocessor systems and peripheral devices Two ports with interrupt-driven handshake for fast response Four programmable operating modes: • Output Mode (both ports) • Input Mode (both ports) • Bi-directional (Port A only) • Bit Control Mode (both ports) Programmable interrupts on peripheral status conditions porta_i clk porta_o cdselect porta_tr portselect ce_n CZ80PIO m1_n iorq_n brdy rd_n bstb_n int_n ieo iei portb_i portb_ o • 8 8 8 Applications • • Programmable, dual - port device Interface for a wide range of peripheral devices such as: • Keyboards • • • Printers Paper table readers PROM programmers etc. CAST, Inc. May 2004 Page 1 CZ80PIO Megafunction Datasheet Pin Description Name Type Description Clock clk In System Clock Interface to Processor Out Tristate controller for buffer for data bus data_i In Data bus input data_o Out Data bus output: rd_n In Read Cycle Status iorq_n In Input / Output Request ce_n In Chip Enable cdselect In Control / Data select portselect In Port B / A select m1_n In Machine Cycle One Interrupt Service Routine int_n In Interrupt Request iei In Interrupt Enable Input ieo Out Interrupt Enable Output Control porta_tri In Tristate controller for buffer for data bus porta_i In Port B bus input porta_o Out Port B bus output portb_tri In Tristate controller for buffer for data bus portb_i In Port B bus input portb_o Out Port B bus output ardy Out Register A ready brdy Out Register B ready astb_n In Port A strobe pulse from peripheral device bstb_n In Port B strobe pulse from peripheral device data_tri register specifies which of the eight data bits in the port are to be outputs and enables these bits; the remaining bits are inputs. The mask register specifies which of the bits in the port are masked. Control logic The control logic consists of the CPU bus interface logic, interrupt control logic and internal control logic. The CPU bus interface logic interfaces the CZ80PIO directly to the CZ80CPU, so no external logic is necessary. For large systems, however, address decoders and/or buffers may be necessary. The interrupt control logic section handles all CPU interrupt protocol for nested-priority interrupt structures. Any device's physical location in a daisy-chain configuration determines its priority. Two lines (IEO and IEI) are provided in each PIO to form this daisy chain. The device closest to the CPU has the highest priority. Within a PIO, port A interrupts have higher priority then those of port B. In the byte input, byte output or bi-directional modes, an interrupt can be generated whenever the peripheral requests a new byte transfer. In the bit control mode, an interrupt can be generated when the peripheral status matches a programmed value. Functional Description The CZ80PIO megafunction is partitioned into modules as shown in figure 1 and described below. Port Logic Each port contains separate input and output registers, handshake control logic and the control registers. All data transfers between the peripheral unit and the CPU use the data input and output registers. The handshake logic associated with each port controls the data transfers through the input and the output registers. The mode control register (two bits) selects one of the four programmable operating modes. The Bit Control mode (mode 3) uses the remaining registers. The input/output control CAST, Inc. Page 2 CZ80PIO Megafunction Datasheet Block Diagram 8 data_i 8 data_o data_tri internal bus Port A Logic portb_i portb_o portb_tri brdy 8 8 8 clk cdselect portselect ce_n m1_n iorq_n rd_n int_n ieo iei bstb_n Control Logic porta_i 8 8 8 Port B Logic porta_o porta_tri ardy astb_n Figure 1. CZ80PIO Peripheral Device Block Diagram Device Utilization & Performance Supported Family Flex Acex Apex Apex2 Cyclone Stratix Stratix-II Device Tested EPF10KE30-1 EP1K30-1 EP20KE30-1 EP2A15-7 EP1C3-6 EP1S10-5 EP2S15-3 LEs 733 731 748 763 583 583 561 Utilization Memory - Performance (MHz) 67 MHz 67 MHz 70 MHz 95 MHz 120 MHz 132 MHz 218 MHz Notes: 1. Optimized for speed 2. Assumes all I/O is routed off-chip CAST, Inc. Page 3 CZ80PIO Megafunction Datasheet Deliverables Netlist License HDL Source License • • • • • • • Post-synthesis EDIF netlist Testbench (self checking) Vectors for testing the functionality of the megafunction Place & Route Script Constraint file Simulation script Documentation • • • • • • VHDL or Verilog RTL source code Testbench (self checking) Vectors for testing the functionality of the megafunction Simulation scripts Synthesis scripts Documentation Verification Methods The CZ80PIO megafunction’s functionality was verified by means of a proprietary hardware modeler. The same stimulus was applied to a hardware model that contained the original Zilog Z80PIO chip, and the results compared with the megafunction’s simulation outputs. Megafunction Modifications The CZ80PIO megafunction can be modified to include additional new ports. Please contact CAST, Inc. directly for any required modifications. Contact Information CAST, Inc. 11 Stonewall Court Woodcliff Lake, New Jersey 07677 USA Phone: +1 201-391-8300 Fax: +1 201-391-8694 E-Mail: info@cast-inc.com URL: www.cast-inc.com This megafunction developed by peripheral controller experts at Evatronix SA Copyright © CAST, Inc. 2004, All Rights Reserved. Contents subject to change without notice CAST, Inc. Page 4