VOTI Wisp648 Manual

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last modified 30-MAY-2010

Content

Introduction 1

In-circuit programming 1

Programming details 3

Power 4

Serial pass-through 5

Firmware upgrading 6

Circuit description 7

Kit construction 8

Troubleshooting 13

Connector pin assignments 13

Connecting a target chip 16

FAQ 17

PCB 1.05 bug 19

Abbreviations and acronyms 21

Document history 22

Introduction

Wisp648 is a serial port in-circuit programmer for Microchip FLASH PICmicro microcontrollers.

The list of target PICs that are supported changes too often to include here, check the Wisp648

page at http://www.voti.nl/wisp648 for an up-to-date list.

In-circuit programming

In-circuit programming (often abbreviated as ICP or ICSP) implies that you program your target

chip while it is in its target circuit. There is no need to extract the chip from its circuit, put it in a

programmer, and put it back in the circuit after programming. Instead you make a connection (a

few wires) between the programmer and the target chip, and you can program it without even

touching the circuit.

To make in-circuit programming possible the target circuit must comply with some rules. The

details are explained in the Programming details section (p 3), but the summary is stated in the

table below. When a resistor is mentioned the stated value is a minimum (higher is OK), and any

circuit is OK that has at least the indicated impedance (for instance: an UL2803 has an input

impedance of at least 2k7, so it can be connected directly to PGC, PGD or PGM pins, which

require a minimum impedance of 1k). Pin 7 and 8 (RxD and TxD) are needed only when the Serial

pass-through (p. 5) is used. The colors correspond to the wires supplied with the Wisp648 kit (but

for readability grey is used in the table instead of black).

Wisp648

Table of Contents

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Summary of Contents for VOTI Wisp648

Page 1: Table Of Contents
Document history 22 Introduction Wisp648 is a serial port in-circuit programmer for Microchip FLASH PICmicro microcontrollers. The list of target PICs that are supported changes too often to include here, check the Wisp648 page at http://www.voti.nl/wisp648 for an up-to-date list. In-circuit programming In-circuit programming (often abbreviated as ICP or ICSP) implies that you program your target chip while it is in its target circuit.
Page 2 Microchip sells two popular programmer/debuggers, the ICD2 and the PICkit2. Beside the DB15 connector the Wisp648 also has two connectors that are compatible with these Microchip programmers. These connectors lack the PGM, RxD and TxD lines, because those functions are not present on the ICD2 and PICkit2.
Page 3: Programming Details
Note that the target circuit must allow the PGM pin to be drawn low – if you connect it to +5V with 10 Ohm resistor Wisp648 will not be able to pull it down.
Page 4: Power
5V too. There are two possibilities for powering the Wisp648 and the target circuit: • The target circuit has its own 5V supply. Do not connect a wall-wart to the Wisp648; the programmer will take its power from the target circuit.
Page 5: Serial Pass-Through
Serial pass-through The Wisp648 can connect your serial port directly to the target chip. This can be very convenient: after programming your target chip you can communicate with it, using the same serial port, without re-plugging cables or other manual actions. This pass-through is done in the Wisp648 firmware, so it is limited to lower baudrates (up to 9600 baud seems to work OK).
Page 6: Firmware Upgrading
• Remove the 16F648A chip from the Wisp648 • Put the second 16F648A chip in the Wisp648 • Verify that the Wisp648 works and has the new firmware (the PC application will report the firmware version). You can now re-use the old 16F648A.
Page 7: Circuit Description
Circuit description Figure 2 : Wisp648 circuit diagram Figure 2 shows the Wisp648 circuit diagram. The MAX232 chip in the lower left corner handles the conversion between RS232 voltage levels and polarity, and the TTL levels and polarity used by the 16F648A PIC chip.
Page 8: Kit Construction
PICkit2 programmers / debuggers, but they lack the TPGM, TRDX and TTXD lines. The row of solder pads can be used to make a permanent connection to a target, for instance when the Wisp648 is installed permanently in a system.
Page 9 Place and solder the three BAT85 diodes. The (black) band on the diodes must be at the side of the white band in the PCB silkscreen (white print on the PCB). Trim the wires. Place and solder the four 1kΩ (brown – black – red) resistors. Resistors are not polar, so it does not matter in which direction they are placed, but for aesthetic purposes it makes sense to have them all point in the same direction.
Page 10 Place and solder the LED. The longer wire must be put in the hole in the middle of the silk ‘symbol’ for the LED. In other words: insert the longer wire in the hole nearest to the DB15 connector. Trim the wires. Place and solder the BC550 transistor.
Page 11 The metal tab corresponds to the thick wide edge on the silkscreen drawing. I prefer to limit the component height of the Wisp648 programmer, so I bend the regulator towards the power connector. This requires a little slack in the wires, so it is easiest to do this before soldering.
Page 12 Cable Strip a few millimeters of the six colored wires and solder them to the female DB015 connector. The solder cups are numbered from left to right: 1 … 8. You use only the top row, the bottom row has only 7 cups.
Page 13: Troubleshooting
Is your power OK? If you use a wall-wart to power the Wisp648, it must supply 9..18 V DC. An AC wall-wart might work, but only for a target circuit that uses very little current (< 100 mA). If you use the target’s 5V to power the Wisp648, make sure that it is really 5.0 V, certainly not 4.5Vor 5.5V.
Page 14 Not used Black centre-pin connector and screw connector: wall-wart The Wisp648 has two power connectors; you can use the one you prefer. The black 2.5 mm centre- pin connector is convenient and matches the connector often found on wall-warts. The screw connector is more reliable and should be used when a more permanent connection is to be made.
Page 15 Ground Not connected The Wisp648 has a PICkit2 compatible pin-header connector. You can use this connector connect to a target board that has a PICkit2-compatible pin-header connector. The table shows the use of the pins. Pin one is the one marked with the triangle.
Page 16: Connecting A Target Chip
(newer PICs) 28-pin skinny DIP The pictures show how the colored wires of the Wisp648 should be connected to various target chips. For readability the black wire is shown here as gray, and the white wire (PGM) is shown in a box on a white background..
Page 17: Faq
PC programs will run on your particular Linux version. I have a Wisp628 The Wisp628 is an older version of the Wisp648. It lacked a number of hardware features that are present on the Wisp648: • No build-in 7805 power supply •...
Page 18 Can I build my own Wisp648? Yes you can. I explicitly allow anyone to build a Wisp648 for his own use. Of course I prefer you to buy a kit or build Wisp648 from my webshop, but for some people even the price of the kit might be too high.
Page 19: Pcb 1.05 Bug
• It is allowed to design and make a Wisp648 PCB, but it is not allowed to have it made for you by a PCB company, nor is it allowed to sell such a PCB, or to provide the PCB design to the general public.
Page 20 2. Instead of using the white wire you could put a pull-down resistor between the PGM/LVP pin of your target chip and ground. A value of 10 .. 100 kΩ should work fine. 3. If your Wisp648 was bought ready-made you can contact me to have it replaced by a corrected version.
Page 21: Abbreviations And Acronyms
On some PICs a floating or high PGM pin can hinder HVP programming. This can be solved by pulling the PGM pin low. This can be done by a simple pull-down resistor in the target circuit. Alternately the Wisp648 has a dedicated line (white wire) that is pulled low at the appropriate moments.
Page 22: Document History
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.
Page 23 • 2007-12-17 : color code for 47R corrected [Aat Koch, Peter Melin, Mikael Halvarsson], one elco is a tight fit [Aat Koch] • 2007-12-15 : FAQ added: Wisp648 identifies itself as Wisp628 [Fris Kieftenbelt]; DB15 connector on the PCB must be male [Rikard Bosnjakovic]; 18F PLL fuse FAQ added; some textual refinements •...