High-Speed Controller Board (2)

In the June 2002 issue we introduced you to the DS89C420, the youngest member of the microcontroller family produced by our ever active friends at Dallas Semiconductor. This controller, although fully downward compatible with other devices from the 8051 series, is much faster and offers loads of extras. This month we continue where we left off by presenting a board which, helped by some free software from Dallas, forms the basis of a powerful yet affordable development system.The 8051 series is still extremely popular with hobbyists as well as professionals. Since the introduction of this microcontroller by Intel in the late 1980’s, a veritable galaxy of development tools, programs and subroutine libraries have appeared which are freely available to anyone with access to the Internet. Although the original controller has been extended with peripheral functions and its clock frequency raised by various manufacturers, the basic architecture of the 8051 core has remained virtually unchanged.

Resistors:
R1 = 1kOhm 
R2 = 39kOhm 
R3,R4 = 10kOhm 
Capacitors:
C1,C7,C8,C9,C12,C13,C16 = 100nF
C2-C6,C17 = 10µ F 25V radial
C10 = 470µ F 25V radial
C11 = 47µ F 16V radial
C14,C15 = 27pF
C18 = 220pF
Inductors:
L1 = see text
Semiconductors:
D1 = 1N4001
IC1 = MAX232CP
IC2 = 7805
IC3 = DS89C420-MCL or -MNL (DIP40, Dallas Semiconductor/Maxim)
IC4 = 74HCT573
IC5 = 62256 (8 x 32k, speed min. 100ns)
IC6 = 74HCT125
Miscellaneous:
JP1 = jumper
K1 = 20-way SIL header
K2 = 34-way boxheader
K4 = 9-way sub-D socket (female), angled pins, PCB mounting
K5 = 2-way PCB terminal block, lead pitch 5mm
S1 = pushbutton with make contact
X1 = 33MHz quartz crystal
PCB, order code 020102-1