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By NICHOLAS VINEN PIC/AVR Programming Adaptor Board; Pt.2 Last month, we described our new programming adaptor board which works in conjunction with an In-Circuit Serial Programmer (ICSP) to program most 8-bit & 16-bit PIC and 8-bit Atmel AVR microcontrollers. Here, we give the details of how to build it and how to use it. A S NOTED LAST MONTH, virtually all the semiconductor devices in the PIC/AVR Programming Adaptor are surface-mount, apart from the diodes and LEDs. This approach has been taken otherwise the PCB would have been impractically large. Even so, the double-sided PCB is fairly densely populated on the topside and has quite a few SMDs underneath as well. However, we have specified SMDs with a “reasonable” pin spacing so they should not be too challenging to solder. 74  Silicon Chip The double-sided PCB measures 116 x 127mm and has plated-through holes and vias. The PCB is available from the SILICON CHIP Partshop and is coded 24105121. It isn’t practical to make the board yourself, given the number of vias, especially as some of them are located under components. The boards we provide not only have plated through-holes but also a solder mask and a silk-screened overlay on both sides to make construction as easy as possible. Figs.4(a) & 4(b) show the component overlays for both sides of the PCB. Install the surface-mount parts on the top first. You can refer to the panel later in this article for a step-by-step procedure on hand-soldering SMDs. Note that most of the SMD components are static-sensitive and so you should ideally build it on an anti-static mat or using some other method to prevent damage to the Mosfets and ICs. Starting assembly Start with the three small dual diodes (D6-D8) and then fit the four siliconchip.com.au Q15 © 2012 100nF 100nF 100nF 1 24105121 IC9 4075B 1 IC12 4069B 1 IC7 4071B 1 IC11 4081B IC10 4081B IC6 4028B 1.1k 13k 1 100nF + 1 470nF Q4 Q24 Q25 220nF 100nF 1 100nF 220 4x 2N7002P Q3 Q27 Q28 Q11 Q23 10F + 100F REG4 34063 VPP VDD PGD GND PGC IC3 4051B Q12 100nF 100nF 47k 100k Q29 Q26 40-PIN ZIF SOCKET 10F 220nF 2.2k 47k 2.2k 2.2k 47k D4 4148 RN1 8x100k LK1 16V + – 47F 25V D1 5819 L1 470pF 220H 100nF D6 BAT54S D8 1 BAT54S Q7 100nF D3 4148 S1 MODE Q16 LK2 100nF 1 100nF 10F 47k RESET 1 100nF IC13 74HC04D 100nF IC17 4028B POWER OFF O/C 1M IC16 LM393 1 D2 4148 1k 47k 68k 100nF 100nF MICRO LED2 POWER ON ON MICRO LED3 33pF x2 100nF Q17 1k LED1 IC14 4013B S5 0.1Ω IC15 OP07 ON REG2 3.3V 100nF BAT54S 1 100nF AVR D7 4.7k PIC MISO CON2 + 47F 25V POWER MOSI RST SCK X1 100F 100F 100F D5 REG3 2.5V CON1 GND Q22 2 VCC VDD 1 Q1 1 10F 100nF 3 – + + + 4004 4 + siliconchip.com.au REG1 7805 POWER OFF 100nF 100nF Q1-Q25: FDS6912A PIC/AVR Programming Board (TOP OF BOARD) AVR ICSP (ABOVE) 1 MOSI 1 24105121 +2.5V VDD VIN IC2 4051B IC1 4051B IC4 4051B MISO SCK RST VPP VDD GND PGD PGC GND VCC GND PIC ICSP (ABOVE) +3.3V 1 GND Q6 Q20 DIP SWITCHES (ABOVE) IC8 4071B 1 7 6 5 4 3 2 1 0 Q8 100nF 100nF Q19 Q18 Q2 Q14 Q1-Q25: FDS6912A 10F Q21 IC5 4051B 100nF 1 Q10 Q13 Q9 +5VSW Q5 2N7002P Mosfets. These diodes and Mosfets look virtually identical so be careful not to get them mixed up. Follow with the 13 FDS6912A dual Mosfets that go on the top of the board. They are in 8-pin SOIC packages and are not all orientated in the same manner so check carefully that each one is the right way around before soldering it in place. These Mosfets usually have both a bevelled edge on one side of the package and a dimple to indicate pin 1 – the position of both is shown on the overlay diagram. There are also 13 ICs (including REG4) on the top of the PCB and they go in next. Again, their orientations vary so you should check each one carefully. Some of the ICs may have a dot or dimple indicating pin 1 but some will only have a bevelled edge so that is the most reliable way to tell which way they go in. Many of the ICs are in identical packages so take care that each type goes in its designated location. Regulators REG2 and REG3 can now be fitted. Solder the three pins and then the tab. Don’t get the two mixed up. Then you can fit the passive SMD components, which consist of eight 100nF ceramic “chip” capacitors, two 220nF ceramic capacitors, three 10µF ceramic capacitors and one 0.1Ω SMD resistor/shunt. It’s now time to fit components to the other side so fit the four tapped spacers at each corner on the top side of the board, using M3 x 6mm screws. That done, flip it over and it will rest flat and level on the spacers rather than the components you have just finished soldering. Refer now to Fig.4(b). There are a further 12 FDS6912A dual Mosfets so fit them now. Again, be careful with orientation as it varies. Follow with the five remaining ICs and then the three passive SMD components: one 10µF and two 100nF ceramic capacitors. You can then remove the tapped spacers and refit them on the other CON3 USB 100nF CON4 + Fig.4: the overlay diagrams for both sides of the PCB. Install the parts as shown here, paying close attention to the orientation of the ICs, Mosfets and electrolytic capacitors. Pin 1 is shown with a dot in one corner of the IC but in some cases there may be no dot and instead, a bevelled edge on the IC package indicates the side with pin 1. +16V +5V PIC/AVR Programming Board © 2012 (UNDER SIDE OF BOARD) June 2012  75 GND Right: the underside of the PCB also carries quite a few SMD ICs plus a 10μF SMD capacitor and two 100nF SMD capacitors This view shows the completed prototype. Take care to ensure that the SMDs are all mounted with the correct orientation (see Fig.4). An accompanying panel describes how the SMDs are soldered in. side of the board, in preparation for the next step. Through-hole components Now we come to the resistors. Check each value with a DMM before soldering it into place. Follow with the five diodes, orientated as shown on the overlay diagram. There are three different types so be sure to put them in the correct locations. Mount the 40-pin production (or dual-wipe) IC socket next, with the notch at the top. Check carefully that its edges are parallel to the edges of the PCB before soldering more than a couple of pins, otherwise the ZIF socket will be crooked when it is inserted Bend the leads of REG1 down 90° 6mm from the plastic body and then mount the tab onto the PCB using the remaining M3 x 6mm machine screw, a shakeproof washer and a nut. Do it up tight, then solder and trim the leads. Fit the 9-pin resistor network next, with its pin 1 (usually indicated by a dot) towards the righthand end of the PCB. The 8-way DIP switch can then go in, with the text right-side-up 76  Silicon Chip as shown in the photos. That done, solder the three LEDs in place with their anodes to the right (flat sides to the left), followed by the MKT and ceramic capacitors. Bobbin inductor L1 is next. There is an extra pad on the PCB so that you can fit different-sized chokes. If you’re using the smaller type, make sure it is soldered across the bottom two holes. You can then fit slide switch S5 which can go in either way, although you may wish to mount it with the stamped “ON” text at the top. Now solder in the 2-way, 3-way and 6-way pin headers (CON5, LK2 and CON1 respectively). Follow with the IDC socket (CON2) and then crystal X1. You can then fit all the electrolytic capacitors with the longer lead though the hole marked with a “+” symbol in each case. The DC and USB sockets go in now. In each case, push them down fully onto the PCB and ensure they are aligned with the edge of the PCB before soldering their pins. Attach the USB socket’s tabs to the mounting pads before soldering the smaller pins. You can now mount the tactile pushbuttons after pushing them down firmly onto the top of the board. Orientate them so that the pins are on the left and right sides. Testing First, check that the power supply is operating properly. Move all the DIP switches to their lower (off) positions. The two pads for LK1 (below the DIP switches) must not be shorted together. If you have a current-limited bench supply, set it for 9V and 100mA and connect it between a convenient ground point and the anode of D5. Otherwise, you can use a 9-12V DC plugpack. Leave S5 in the “off” position and then switch on the power supply. Check the output of REG1, at its right-most pin. You can use the tab or mounting screw to connect the ground probe. You should get a reading very close to 5V. Assuming that’s OK, switch on S5 and check that the green power LED lights up. There are two small round pads to the right of LK1, below the DIP switch bank, labelled “+” and “-”. siliconchip.com.au acitance between pins 6 & 8 of the ZIF socket. This should be around 10µF. Much less than that indicates a fault. If that all checks out OK, chances are good that your programming adaptor board is working properly. You could test other modes in a similar manner, referring to the relevant microcontroller data sheets, but it would take a while to check all the various modes. It’s now time to install the ZIF socket, with the lever towards the top of the board. Support the PCB underneath the socket and press it down hard. Its large pins are a tight fit but they should go in with some effort and it won’t easily come off again unless you really need to remove it. The unit is now ready for use. Using it These allow you to check the output of REG4, which should be close to +16V. However, since they are quite close together, you may find it easier to measure between TP1 (the positive test point) and the same ground point you used earlier, eg, REG1’s tab. Confirm that REG4 is providing around 16V. If not then switch off and check it and the surrounding circuitry for faults such as incorrectly orientated components or bad solder joints. Assuming that it’s OK, measure the output of REG2 at its tab, relative to the same ground point you used earlier. You should get 3.3V. You can now disconnect the power supply and short LK1’s pads together using a small blob of solder. Set up the DIP switches for the PIC18F2xJ5x series of microcontrollers, as shown in Fig.5. Apply power, turn power switch S5 on and then press the “Micro Power On” pushbutton. The yellow LED should light up. If the red LED lights up, switch off and check for faults in the power supply circuitry. Check the voltage at pin 32 of the ZIF socket (adjacent to pin 9), relative siliconchip.com.au to a convenient ground point, eg, the tab of REG1. You should get a reading of around 3.3V. Check that pins 8 and 31 read very close to 0V. They should not be floating which normally gives a reading somewhat above 0V. Now set your DMM to continuity mode and check that there is a good connection between pin 1 of the ZIF socket and the VPP pin of CON1 (rightmost). Check this in both directions, ie, swap the multimeter probes around and ensure that there is a connection either way. You can then perform the same test to check that ZIF socket pin 40 (upper-right) is connected to PGD (CON1, third-from left) and that socket pin 39 connects to PGC, the secondfrom-left pin of CON1. Now use the DMM to check that the five right-most pins of CON1 are not connected to each other. You may get a brief beep out of the multimeter with the probes between VDD and GND due to power supply bypass capacitance. There should not be continuity between PGD, PGC and VPP. Assuming that your DMM also has a capacitance mode, measure the cap­ Figs.5 & 6 provide the instructions you need to operate the unit. These can be copied and laminated to keep with the unit. Note that it’s generally not a good idea to change the positions of the DIP switches while the unit is switched on as the design assumes that all the logic is static. This also avoids the possibility that you might accidentally change to the wrong mode while a microcontroller is in the ZIF socket and powered up. Note that some PICs require 5V for programming even though they can run at 3.3V (eg, PIC12F675). For this reason, it’s generally best to program with a 5V supply if the micro is rated to operate at 5V, which may require different DIP switch settings than those shown in Fig.5. If in doubt, check the data sheet. Generally, LK2 can be left in its default position, with the jumper shunt across the bottom two positions. That way, the in-circuit programmer receives power at the same time as the micro and so it won’t try to “probe” it when it is unpowered. But if the programmer is to provide power for the micro and you want to be able to switch it using the on-board power on/off buttons, you can move the shorting block to the other position. In this case, the programmer’s VDD pin is the source of voltage for the micro power supply circuitry, including the electronic fuse (although incircuit programmers normally provide some form of current limiting too). Programming dsPIC30s We last published a PIC programJune 2012  77 Setting The DIP Switches & Programming The Device PIC/AVR Programming Adaptor Board Device Selection PIC12F-, PIC12HV- A All A 50x, 51x, 526, 63x, 67x, 68x, 690, 720, 721, 785, 145x, 150x, 1823-1825, 1828, 1829 PIC16F-, PIC16LF- B 54, 7x, 8x(A), 540, 61x, 62x(A), 648(A), 716, 1826, 1827, 1847 C 722-726(A), 737, 767, 882, 883, 886, 913, 916, 151x, 17xx, 1906, 193x D 707, 747, 777, 87x(A), 884, 887, 914, 917, 1904, 1907 PIC18F-, PIC18LF- A 1xK2x D 4x1x, 4x2x, 4x3x, 4x8x, 4xK2x, 4xK8x B 1220, 1230, 1320, 1330 E 1xK5x G 4x5x C 2x1x, 2x2x, 2x8x, 2xK2x, 2xK8x F 2x5x H 2xJ1x, 4xJ1x, 4xJ5x M *2xJ5x PIC24E- I All PIC24F- I J16MC102 PIC24H- I J16GP102, J16MC102, J32MC202, J32MC204, J16GP304, J32GPx0x, J64GPx0x, J120GPx0x J 0xKA102, 0xKLx01, 0xKLx02 K JxxGAx0x L JxxGB00x dsPIC33E- I All dsPIC33F- I J12GP202, J12MC202, J32GP30x, J32MC30x, J64GPx0x, J64MCx0x, J128GPx0x, J128MCx0x ATtinyATmega- N 13(A)(V), 15L, 25/45/85(V) O 26(L), 261/461/861(A)(V) Q 48/88/168/328(P)(A)(V), 8(A)(L) P 2313(A)(V), 4313 Q 48/88 R 16/32(A)(L), 164/324/644/1284(P)(A)(V), 8535(L) x = any digit 0-9 (P), (A), (V), (L) = optional letter suffix A E I M P On B 1 2 3 4 5 6 7 8 On F 1 2 3 4 5 6 7 8 On J 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 * (PIC18F-) On 1 2 3 4 5 6 7 8 M Q On C 1 2 3 4 5 6 7 8 On G 1 2 3 4 5 6 7 8 On K 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 * (PIC18LF-) N R On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 D H L O On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 On 1 2 3 4 5 6 7 8 Setting shown for Setting shown for (AVR only) External clock may 3.3V programming; 3.3V programming; be enabled. Use some micros may need 6 7 8 5V not recommended 6 7 8 6 7 8 4 5 6 only if necessary. 5V for programming. and may be disabled. Fig.5: this diagram shows the supported devices along with the relevant DIP switch configuration. Look up the part series in the table at the top, then find the letter code for the particular suffix and set the DIP switches to the corresponding configuration. There may be some parts not listed here that can be programmed in one of the modes. Setting shown for 5V programming; 3.3V also suitable. 78  Silicon Chip siliconchip.com.au PIC/AVR Programming Adaptor Board Step-by-Step Guide 1 Set power switch in "off" position 2 Look up device to be programmed in Device Selection sheet and set DIP switches as shown. 3 Lift ZIF socket level and insert microcontroller with pin 1 at upper-left. Hold microcontroller steady and push lever down until it locks. 4 Launch PC software, select correct target device and connect programmer to CON1 or CON2. Do not connect both PIC and AVR programmers at the same time. 5 Switch on power to programming adaptor board. Check that green LED is lit. 6 Press “Micro Power On” pushbutton. The yellow LED should light up. If red LED lights instead, press “Micro Power Off” button and re-check DIP switch positions. 7 If providing external microcontroller power (eg, from PICkit3), enable it now. 8 Check device signature using PC software. This is automatic with Microchip MPLab. Assuming it is correct, you can then proceed to program, read and/or verify the flash memory in the target microcontroller as required. 9 If providing external microcontroller power (eg, from PICkit3), switch it off now. 10 Press “Micro Power Off” pushbutton and switch board power off. 11 Lift ZIF socket lever. The microcontroller can be safely removed. 39 10F 6 10F 34 7 32 39 32 10F 12 Insert a wire link in the ZIF socket as shown here to program PIC18F2331 or PIC18F2431 micros in mode C . An extra 10F tantalum or ceramic capacitor is required to program PIC18F44J10 or PIC18F45J10 micros in mode D . An extra 10F tantalum or ceramic capacitor is required to program PIC24FVxxKA301 but not PIC24FxxKA301 micros in mode K . An extra 10F tantalum or ceramic capacitor is required to program PIC24FVxxKA302 but not PIC24FxxKA302 micros in mode K . Fig.6: here are the instructions for using the unit, along with the special case devices which can be programmed with an extra wire link or 10µF capacitor inserted in the ZIF socket. Ensure that this extra component is well clamped at both ends before applying power and take care with tantalum capacitor orientation. mer in the May 2008 issue. This was called a “Low-cost Programmer for dsPICs and PICs” and it connected to the PC via a serial port. That project required the now-defunct WinPIC softsiliconchip.com.au ware which is still available but is not being updated to suit newer micros or the latest Windows operating systems. Most constructors would be better off with the new design described here because it can handle a larger portion of the PIC range, works with up-to-date software and is easier to use. The one thing the previous unit can do that this one can’t is to program dsPIC30F miJune 2012  79 Soldering In The Surface Mount Devices (SMDs) Installing an SMD IC: (A) place a small amount of solder on the top-right pad; (B) re-melt the solder & slide the IC, the solder the diagonally opposite pad; (C) solder the remaining pads (ignore solder bridges); (D) remove the excess solder using solder wick and clean up using isopropanol. If you don’t have a solder reflow oven, you can solder the SMDs one at a time, by hand. With a little practice, this isn’t too difficult, especially since the parts used in this project have a relatively large spacing between pins. You will need a temperature-controlled soldering iron with a mediumsize or smaller conical tip, a magnifying glass (preferably a magnifying lamp), angle-tip tweezers, some desoldering braid (or solder wick) and a syringe of no-clean flux paste (Jaycar Cat. NS3039, Altronics Cat. H-1650). Don’t try to attempt the job without these basic tools, otherwise you could wreck both the ICs and the board. You don’t need to use a very thin tip on the soldering iron. In fact, using a thin tip can make the process more difficult when it comes to applying enough heat to the solder wick and getting the solder to reflow properly. The standard tip supplied with most good irons should be sufficient and a medium to fine conical tip works well. Be sure also to use fine, good quality solder (0.71mm diameter solder is ideal). Step-by-step procedure The step-by-step procedure for soldering in each SMD is as follows: (1) Remove one part from the tube or tape packaging. With tape, peel back the clear layer using tweezers to expose one device at a time. Take care not to drop the smaller devices as they can be impossible to find if they land on the floor. (2) Find the location for that component on the PCB. Place the board flat on the workbench with the right side up and orientated so that pin 1 will be at upper-left. (3) Apply a tiny amount of solder to the top-right pad for the device (or top left if you are left-handed). To do this, briefly touch the pad with the soldering iron and add a dab of solder – just enough Current Limit Adjustment Once you have finished programming a chip, by default it will immediately begin executing the new program code. However, while the electronic fuse current limit has been chosen to supply sufficient current for programming the micro, in some cases it may not be enough once it starts operation, especially with high-speed parts such as dsPIC33s. In this case, the micro power will trip off immediately after programming is complete and you will lose the ability to perform further operations, even if you reset the micro power supply. There are two solutions to this. The first is to set the in-circuit programmer to hold the micro in reset once programming is complete. This can be done in Microchip MPLAB via the Programmer menu using the “Hold In Reset” option. However, this option is only available when the programmer is operating normally so you have to do this first. The other option is to increase the current limit to allow the micro to operate once it is programmed. This can be done by reducing the value of the 68kΩ feedback resistor across IC15 (adjacent to D2 on the PCB). For example, substituting a 47kΩ resistor increases the current limit to around 130mA. Avoid increasing it much more than this; if the current limit is high enough, you risk damage to the micro under fault conditions. 80  Silicon Chip so that you can see smoke from the flux – then quickly remove the iron. You should now be able to see a small solder bulge on that pad (check with a magnifying glass if unsure). (4) Clean the tip of the iron with a damp sponge to remove any excess solder. (5) Place the component next to (but not on) the pads. If you are righthanded, place it slightly to the left of the pads and vice versa. (6) For leaded components (ICs, Mosfets and diodes), check that the leads are resting on the PCB surface. Capacitors and resistors should lie flat on the board. For resistors, keep the label side up. (7) Check that the component orientation is correct. For ICs, ensure that the corner dot/dimple or bevelled edge is on the lefthand side. SOT-23 FETs and dual diodes have a triangular pin layout so the necessary orientation should be clear. Other components (resistors, capacitors) are not polarised and orientation is not important. (8) Grab the part by its sides using a pair of angled tweezers. (9) Use the soldering iron to melt the solder on the top right pad, then gently slide the part along the board and into place. Remove the soldering iron immediately it is in place. This process should only take a couple of seconds, to avoid overheating the pad and the component. cros. While a small range of dsPIC30s is still available, they have essentially been made obsolete by the dsPIC33F and dsPIC33E/PIC24E series. As a result, we don’t expect many people still use them. If you need to program one, you could use the May 2008 programmer or alternatively, build a programming jig on stripboard. USB power Finally, if you are going to run the board from USB power, it generally draws less than 100mA. However, depending on the exact configuration and the micro being programmed, it could draw more so it’s a good idea to run it from a computer host port or a powered hub, especially since it has no circuitry to negotiate power allocation from the host computer. siliconchip.com.au Don’t worry about getting it in exactly the right place the first time. Just try to avoid getting any solder on the other pins. As long as you do that, repositioning the part is easy. (10) If the part is not exactly lined up with the pads, simply re-melt the solder and nudge it until it is. Wait a few seconds between each attempt. When the part is correctly lined up, all its pins will be centred on their pads. (11) Once you are happy with the alignment, re-check that the component orientation is correct, then rotate the board 180° and solder the pin at the opposite corner. It shouldn’t move much during this step but if it does, reheat the joint and adjust it as necessary. (9) Now solder the rest of the pins. The parts used here can be successfully soldered one pin at a time without forming bridges but don’t worry if you do get bridges as they are easily removed later. It’s more important to make sure that solder has flowed onto all the pins and pads. (10) Even if you have no bridges, it’s recommended that you apply a thin layer of flux paste along both rows of siliconchip.com.au pins, towards the outside. A thin layer should be enough (you can always add more later if necessary). You can now remove any excess solder. That’s done by placing a length of solder wick immediately alongside (but not on top of) some of the pads. Now place the soldering iron on top of the solder wick, pressing it down onto the board, while gently sliding the wick towards the solder on the pads. As the wick heats, it will start to melt the flux and the excess solder, creating visible smoke. At that point you can slide it right up against the pins. Most of the excess solder should then be sucked into the braid. Finally, slide the wick along the board away from the pads and lift it and the soldering iron off the board. At all times, you should be pressing down onto the PCB only while sliding the wick along it. The whole process should take no more than about 5-6 seconds. Don’t worry if some solder bridges are left behind – rather than applying the heat for too long, it’s better to remove what’s left with a second pass. When you are finished, the pins should be left with a near-perfect amount of solder and no bridges. The reason we recommend that you do this even if there are no visible bridges is that it virtually guarantees good solder joints by reflowing the solder with the additional flux. Otherwise, it’s possible to get a joint that a cursory check suggests is OK but on closer inspection, the solder has adhered to the component pin but has not flowed down onto the pad below it. (11) Repeat the above process for the other side of the component. (12) Inspect the part using a magnifying glass to check for any solder bridges or bad joints. If there are solder bridges, apply a little flux and then use the solder wick to clean it up. (12) If you are using no-clean (noncorrosive) flux (ie, the recommended type) then you theoretically don’t need to clean off the flux residue. However since this board won’t necessarily be installed in a housing, it’s a good idea to clean the sticky flux off it using pure alcohol (eg, isopropanol). Finally, if you do get flux on your hands, be sure to wash them as it SC can be toxic. June 2012  81