22
Programmable Intelligent Computer. This chip is the mother of all PIC chips,
functionally close to the current 16C54. General Instruments sold its product to
Microchip. As far as I know Microchip has never used PIC as an abbreviation, just as
PIC. Recently Microchip has started calling its PICs microcontrollers PICmicro
MCU's.
RTS
Request To Send : An RS232 signal that was used by the computer to signal to the
modem that it (the computer) wanted to send data.
RxD
Receive Data : RS232 data line. As seen from a DTE (Data Terminal Equipent) this is
the line on which serial data is received.
TxD
Transmit Data : RS232 data line. As seen from a DTE (Data Terminal Equipent) this
is the line on which serial data is received.
Vcc
Name for the positive power supply connection of an IC. The cc part might be derived
from ‘common collector’, from the times when an IC could contain a lot of NPN
transistors that all had their collectors connected to the positive supply rail.
Typical supply pin labeling
bipolar transistor FET
V
CC
V
DD
V+
V
S+
Positive supply voltage
V
EE
V
SS
V−
V
S−
Negative supply voltage or ground
Vdd
Name for the negative or ground (0V) power supply connection of an IC. The dd part
might (in analogy with Vcc) be derived from ‘common drain’.
Vpp
Microchip’s name for the voltage level on the MCLR pin that will enable the
programming mode of a PIC chip.
Vss
Name for the negative or ground (0V) power supply connection of an IC. The dd part
might (in analogy with Vcc) be derived from ‘common source’.
WISP
Wouter’s In-System (PIC) Programmer : My first PIC programmer design, with some
unusual features: serial interface without a MAX232 or similar, but multiple WISPs
could be connected to one serial port; it could vary the target Vdd voltage using a D/A
converter that had to be calibrated; used pin RA4 to switch the ~ 13V Vpp directly
(not possible with later PIC types). It used a 16c84 or 16F84(A). The design was
published on the web, but I never sold this programmer.
“Tom Poes en de Wispen” is a comic story by the late Dutch author Maarten Toonder.
In this story wisps are bees or wasps that cause the victim of their strings to predict
the future. I liked this as analogy for a microcontroller programmer, so I choose a
wasp as symbol for Wisp series of programmers.
Wisp628
Successor to the WISP programmer. Used a 16F628(A) or 16F648A and a MAX232.
No daisy-chaining, no variable Vdd. Sold as programmed PIC, as kit, and build.
Needed an external circuit (‘dongle’) to program chips that require the Vpp-before-
Vdd sequence.
Wisp648
Successor to the Wisp628 programmer. Adds a build-in ‘dongle-circuit’, 7805
regulator, activity LED, and connectors compatible with ICD2 and Pickit2.
Document history
•
2010-05-30 : jumper text corrected; one elco value changed
•
2009-07-18 : the LED blinks three times, not two [Henk de Vries and many others]
•
2009-05-08 : the power-short option now has a 3-pin header instead of the 2-pin header
