About the article

Parallel JTAG Interface

Parallel JTAG Interface
This circuit is for an interface between the parallel port of a PC and a socalled JTAG interface. This type of circuit was originally developed by a company called Altera, which referred to it as the ‘Byteblaster’.The version described here is compatible with the Byteblaster (electrically it is almost identical). This has the advantage that programs written for use with the Byteblaster can also be used with this interface. The circuit itself is very simple. K1 is connected to the parallel port of the PC, whereas signals D0, D1 and D6 are brought to the JTAG connector via IC1. The output of the JTAG connector (TDO) is in turn fed back to the PC’s BUSY signal via IC1. Pin 7 of the JTAG connector is used to provide an extra output. This signal is brought to the SELECT input of the parallel port via IC1.
Downloading of this magazine article is reserved for Elektor Members only.
Already a member? click here to log in.
Products
Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Resistors:
R1-R5,R9-R12,R15-R18 = 100Ohm
R6,R7,R8,R13,R14,R19,R20 = 10kOhm
Capacitors:
C1 = 100nF
Semiconductors:
IC1 = 74HCT244
Miscellaneous:
K1 = 25-way sub-D plug (male), PCB mount
K2 = 10-way boxheader
PCB, order code 020008-1
Loading comments...