Application of PSD813 Device in Single Chip Microcomputer System

With the widespread application of single-chip microcomputer systems, their functions are constantly strengthened and their integration is increasing. However, in the traditional single-chip microcomputer system design, many discrete devices must be used to form the peripheral circuits of the single-chip microcomputer, such as address latches, PLDs, RAMs, EPROMs, etc., which makes the entire system very complicated, reduces reliability, and increases power consumption costs. Since the requirements of each system are not consistent, the above peripheral discrete device circuits must be repeatedly designed when developing each single-chip microcomputer system, which prolongs the development time, greatly reduces work efficiency, and also wastes a lot of manpower and material resources. With the rapid development of science and technology, especially large-scale integrated circuit technology, single-chip microcomputer peripheral integrated chips have also emerged and developed. WSI's programmable single-chip microcomputer universal peripheral interface chip (PSD) can integrate multiple peripheral devices required by the single-chip microcomputer into one chip, and can achieve the so-called seamless connection (noglue) with the single-chip microcomputer, which greatly simplifies the design, saves resources, and significantly improves the reliability of the system. Since the PSD series products cater to the requirements of single-chip microcomputer application system development, its advanced design concept has brought many benefits to the majority of single-chip microcomputer developers. Therefore, replacing single-chip microcomputer peripheral discrete devices with PSD or other similar devices has become a major trend in single-chip microcomputer development.

1 PSD813 Series Product Features

As the latest member of the PSD series, the PSD813 series devices inherit the excellent characteristics of previous generations of PSD products, while adopting new technologies and processes to improve some of the shortcomings of previous PSD devices. The flash memory and programmable logic of the PSD813 have online programmable characteristics, which is very helpful for realizing simple and flexible embedded design solutions. The PSD813 device also integrates an optimized "microcontroller macro unit" logic structure, which allows the system address/data bus to be directly connected to the PSD internal registers, simplifying the communication between the MCU and its external devices. In addition, the PSD813 also has the following key features:

(1) 1M-bit internal large-capacity FLASH ROM, 256K-bit E2PROM (813F1) or FLASH OTPROM (813F2), 16K-bit SRAM, where the FLASH ROM can be configured as 128K×8 or 64K×8 and divided into 8 blocks of equal size, which can be accessed by the user-specified address, and the access time includes address latching and PLD decoding. The SRAM can be configured as 2K×8 or 1K×16.

(2) Simultaneous programming of FLASH or EEPROM/OTP ROM flash memory. Code from one memory can be programmed while the other is executed. The EEPROM/flash boot memory is divided into four equal-sized blocks that can be accessed by user-specified addresses.

(3) With 16 output macrocells and 24 input macrocells based on flash. Therefore, the PSD813 can effectively implement a variety of logic functions, including state machines and address decoders for internal and external control. These logic functions require microcontroller software and hardware interaction. The built-in PLD provides three dedicated external chip select outputs, allowing up to 19 external chip selects.

(4) 27 reconfigurable I/O ports can be used as MCU I/O, PLD I/O, latched MCU address output or special I/O ports to provide up to 19 external chip select signals, and 16 of the I/O ports can be configured as drain outputs.

(5) Programmable power management supports two separate low-power modes, and the zero-power CMOS technology allows operation with current as low as 10mA (at 5V Vcc). The device can automatically detect the cessation of microcontroller activity and put the PSD into a low-power state.

(6) The built-in JTAG serial port enables in-system programming and debugging of the device in the factory or on-site.

Because PSD813 has the above characteristics, it can easily perform previously complicated tasks such as I/O reconstruction and expansion of microcontroller address space, and can be flexibly designed through programming to achieve compatibility with different types of microcontrollers, making microcontroller development, especially peripheral circuit design, simple.

2 Connection between PSD813 and MCU

The application example in this paper is based on a fully digital ECG system, as shown in Figure 1. Due to the working requirements of the system, a dual CPU structure (DSP-80C552) is used, with external peripherals such as 160×128 LCD display, serial thermal printer, 4×4 keyboard, etc. The system bus is designed to be 8 bits. Since the system requires the storage of a large amount of ECG data, a large-capacity SRAM of 512K is used. Among them, the DSP (TMS320F206 of TI Company) is mainly used for the filtering calculation, analysis and control printing of ECG waveforms. 80C552 is used as the main program and human-machine interface control and A/D acquisition. Since the 51 single-chip microcomputer has many peripherals, in order to save costs and reduce power consumption, PSD813 is used as an external program memory and address decoder, and is used for port expansion. Actual use shows that the system works normally.

3 PSDsoft software application

PSD813 is developed on the basis of hardware using the dedicated development software PSDsoft. PSDsoft is a set of software tools that runs under Windows environment, uses visualization technology for programming, and has convenient human-computer interaction functions. And because the software is highly integrated, each step of operation is carried out under the same interface, so it is very convenient to use.

From the flowchart shown in Figure 2, we can see that in the PSDsoft software environment, the development of the PSD813 device, from the writing of the Abel file, the configuration of the hardware characteristics, to the writing of the target file, can be easily completed. In addition, the PSDsoft software also provides real-time simulation of the PSD device and can realize the C language disassembly of the target file.

Due to limited space, only the Abel file is written for reference: module c51_813

title 'WSI ＰＳＤ８３Ｆ1 design template for ８Ｃ５1 fa m-

ily microcontroller;

"PIN ＤＥＣＬＡＲＡＴＩＯＮＳ

bhe pin 49; "pin 49, byte high enable or CNTL2

wr pin 47; ″pin 47, write line or CNTL0

rd pin 50; ″pin 50, read line or CNTL1

reset pin 48; ″reset input, active low

a15, a14, a13, a12, a11, a10, a9, a8, pin 39, 40, 41, 42, 43, 44, 45, 46; "A ddress bus

a7, a6, a5, a4, a3, a2, a1, a0, pin 30, 31, 32, 33, 34, 35, 36, 37, "Addr essbus

"********Port A,B,C,D pin declaration******************

addr_out0...addr_ out7 pin; ”address out, Port A pins

"Address output

WSIPSD PROPERTY ′Address_Out Aout[7:0]:addr_out t

[7:0] PortA′;

addr_out8． ． adr_out15 pin; ″address out, Port B pins

"Address output

WSIPSD ＰＲＯＰＥＲＴＹ ′Address ＯｔｔＡｏｔ《15:８]：addr

out[15:8] PortB′

a16,a17,a18 pin 18,17,14; ″pc[2：4],a[16:18]

"Extend Address output

LCD_ce pin 11; ″pc7, the signal of LCD

SRAM_ce pin 9, ″pd1, the ce of 512K SRAM

ale pin 10; ″pin 10 address latch enable or PD0

CSI pin 8; "pin 8, / CSI or pd2

fs7, fs6, fs5, fs4, fs3, fs2, fs1, fs0 node; ″Main Flash

Segment chip selects

rs0 node; "PSD SRAM chip select

CSIop node; "PSD control and I/O register

jtagsel node; ″Selects JTAG port active using a prod uct term

Ｘ＝． x. ; "Don't care symbol

address = [a18. ． a0]; ″De-muxed microcontroller

address signals

EQUATIONS

jtagsel = 0;

fs0 = (address ＞=＾h2000 & address ＜=＾h2FFF);

"Address of ROM

fs1 = (address ＞=＾h3000) & (address ＜=＾h3FFF);

fs2 = (address ＞＝＾h4000) & (address ＜＝＾h4FFF);

fs3 = (address ＞=＾h5000) & (address ＜=＾h5FFF);

fs4 = (address ＞=＾h6000) & (address ＜=＾h6FFF);

rs0 = (address ＞＝＾h７７00) & (address ＜＝＾７７ＦＦ);

ＬＣＤ＿ｃｅ＝（ａｄｄｅｓ＞＝＾７８８） &（ａｄｄｒｅｓ＜＝＾ｈ７ＦＦＦ）;

csiop = (address ＞=＾h8000) & (address ＜=＾h80FF);

SRAM_ce=! (! a16 &! a17 &! a18) # ((address ＞=＾h8100 & (address ＜=＾hFFFF)); Address

of RAM

end c51_813

Because PSD813 has a high degree of integration and strong online programming capabilities, its application has greatly improved the development speed, system stability and flexibility of the microcontroller compared to traditional design methods. This should become a development direction of the microcontroller application system.

However, the internal data bus of PSD813 is 8 bits, so although PSD813 can be directly connected to 8-bit MCU, when connected to 16-bit single-chip microcomputer, two PSD813s must be used to form a 16-bit multiplexed and non-multiplexed bus structure interface. And due to the connection rules between 16-bit single-chip microcomputer and external memory, when two PSD813s are connected to 16-bit single-chip microcomputer, their address line connection must be circularly shifted once to ensure that the CPU can correctly receive the high and low instruction bytes in the two PSD813 ROMs at the same time when working.