Wichit Sirichote, wichit.sirichote@gmail.com
New design 8051 microcontroller kit. Designed for school students for basic learning the microcontroller technology.
This is my new design the 8051 kit using 7-segment display and hex key monitor. The design is simple, small number of components and cheap. The size is compact, 5.3x5.7 inches. The keypad is ergo design for young students. The kit is 8051 based microcontroller. So many chip makers produce the 8051 core microcontroller. The kit is available for both preassembled and kit form.
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| Figure 1: 8051 Microcontroller kit |
A simplified block diagram of the 8051 Microcontroller kit is shown in Figure 2. CPU is AT89S52 with 8kB monitor program. The external memory 32kB is decoded as the code and data memory. User program can be tested with this RAM. I used the PLD decoder logic for compatibility with 8051SBC. The display however is now using the 6-digit 7-segment LED. The 8-bit debugging LED and CY LED are also provided.
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| Figure 2: Block diagram. |
Hardware descriptions: U5 is CMOS Microcontoller, AT89S52. It uses internal Flash memory as the monitor program. For external memory, the microcontroller generates bus signal for interfacing U2, the 32kB SRAM. U6 is programmable logic device, GAL16V8D. It is used to decode RAM and memory mapped I/O devices.
U3 is decoded as the external memory at 0x0100. It drives 8-bit debugging LED. JR1 is 16-pin text LCD interface header.
Q3, KIA7042 is brownout reset chip.
U10, 74HC573 port2 drives the segment of 7-segment LED, U8 and U9. U11, 74HC573 port1 drives digit signals of 7-segment LED. Bit 6 drives CY LED and bit 7 drives speaker.
U12, 75HC541 is 8-bit input port. It reads row signals from keypad.
U4, MAX232 converts TTL level to RS232 level.
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| Figure 3: Hardware schematic (click to enlarge). |
PLD equations : U6 is a PLD chip used to select the memory and I/O ports. The address and I/O spaces can be programmed using PLD equations. The source file of PLD equations is shown in Figure 4. The PLD compiler is WinCupl. The output file, JEDEC will be used to program the PLD chip by a PLD programmer.
Name 8051Kit ; /* *************** INPUT PINS *********************/ /* *************** OUTPUT PINS *********************/ RAMCE = !A15; RAMOE = !A15 # (RD & PSEN); RESETH = !RESETL; !GPIO1 = WR # A15 # A10 # A9 # !A8 # A1 # A0; !LCD_E = (RD & WR) # A15 # A10 # A9 # A8; PORT0 = RD # A15 # A10 # !A9 # A8 # A1 # A0; !PORT1 = WR # A15 # A10 # !A9 # A8 # A1 # !A0; !PORT2 = WR # A15 # A10 # !A9 # A8 # !A1 # A0;
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| Figure 4: PLD equations. |
Hardware specification:
Processor: AT89S52 microcontroller, 11.0592MHz 8kB monitor program.
Memory: 256 bytes onchip memory, 32kB external code and data memory, 62256
I/O port: Onchip P1 and P3.
Timer/counter: 16-bit timer 0,1,2.
Watchdog: Onchip Watchdog reset
RESET: Brownout reset chip, KIA4072.
Decoder: PLD memory and I/O decoder chip, GAL16V8
Display: Red color, 6-digit high brightness 7-segment LED, LTC4727
8-bit debugging LED, Carry flag display and P1.7 LED.
Keypad: 16-hex keys, 9 function keys and 3 CPU control keys.
Serial port: RS232C 9600 8n1, male connector.
LCD: 16-pin CPU bus interface for text LCD.
Expansion: 40-pin header.
Electrical Power consumption 80mA @+5VDC.
Mechanical Dimensions: 5.7 x 5.3 inches
Software: Monitor program was written with c language and low level functions written with assembly code. The user manual provides source code listing. Students can learn and modify it.
| Figure 5: 20x2 Text LCD with direct bus interface. |
Kit form: Kit is available at ebay. Check out with 8051 kit keyword. The kit includes PCB, components, preprogrammed monitor code and PLD chips.
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| Figure 6: 8051 Kit form. |
Download User's Manual, Construction Manual, 8051 Hex code table. Monitor code in hex file.
Turn the 8051 kit into BASIC-52 CONTROLLER