Hi all,
before I start, I’ll freely admit I’m a complete noob to PIC’s and a relative amateur at electronics, so don’t ask me anything about them, but I am quite proficient at building things and soldering.
Yesterday afternoon, I bought the K8048 kit at one of a well known chain of electronics stores in the UK. Realising that my laptop doesn’t have a serial port, but thinking my Desktop does, I chipped in for a USB - Serial adapter too. (I’m not on my own here…maybe Velleman should CLEARLY state, on the OUTSIDE of the packaging, that a genuine serial port is compulsory!..Not a problem though, as I can use the adapter elsewhere.) We’ll get to this in a minute.
Anyway, I built the kit as per the instruction booklet, then made up the serial cable. I would like to suggest an amendment to the placing of the RS232 socket on the PCB…Could it be moved outwards slightly, in future PCB layouts, so that the male d-sub cover doesn’t have to be removed to make a connection? I’m digressing slightly, so back to building the kit…
Following the (mostly-correct) instructions, after reading the preceding page (5 for English-speakers) where it clearly states “AXIAL COMPONENTS ARE TAPED IN THE CORRECT MOUNTING SEQUENCE!” I was left wondering where ZD1 was. Again, an amendment could be helpful…“AXIAL COMPONENTS ARE TAPED IN THE CORRECT MOUNTING SEQUENCE! EXCEPT ZD1, WHICH IS PLACED LAST TO AVOID CONFUSION WITH D1 TO D7.”
Although the guide on soldering is quite good, where possible, I like to re-heat the pads on the component side and feed in a little more solder. This ensures a good contact, especially at C8, R21, R26, R27, R28, R31 and SW4, where PCB tracks are found on the component side. Maybe I’m being anal, but there is the possibility that a via is not connected during manufacturing…re-soldering component-side reduces the opportunity for problems to arise. Maybe this could be included on page 9, where the following line could be added…“The visible tracks on the component-side should be re-heated and re-soldered to ensure proper connection, following completion of the PCB-side soldering. Points of interest are C8, R21, R26, R27, R28, R31 and SW4”
This is especially relevant if you consider that this kit is available to ANYONE wandering through an electronics store, looking for something for young Timmy to focus upon for his future career and fortune. Mums
and Dads often ignore difficulty ratings, or don’t even see them due to the SMALL PRINT. This kit is no exception to marketing ploys. I don’t find “Advanced” printed anywhere that is visible on the outer package. It
is not until the kit is purchased and opened, that the customer is informed of the “difficulty rating”. And that is after the cash has been spent. How many parents are willing to spend further cash on ‘projects’ that Timmy ‘may’ not be competent to complete? How many parents are going to be wary of other Velleman products?
I digress again, so…Following the successful completion of the kit build, the next step was the Serial connection. Having removed the male d-sub cover and connecting to the K8048, I now ran into the USB - Serial adapter not allowing the PC to see the hardware. Research brought me here and the numerous problems were whittled down to components fitted the wrong way, in-correct PSU voltages being used, or the USB - Serial issue.
Reversal of components I can understand, as we’re not all competent electronics techicians and the packaging doesn’t really indicate an advanced knowlegde as a requirement.
PSU voltages - The instructions list, in the specifications, a power supply “12 to 15V DC, min 300mA, non-regulated adapter” then supplies a list of suitable PSU’s.
The USB - Serial issue. Again, nowhere on the outer packaging, does it state that a universal USB - Serial adapter is not sufficient for this application.
This is a bone-of-contention for a lot of the people who have bought this kit. Had it been CLEARLY stated that a USB - Serial adapter is not sufficient, I’m sure a lot of consumers would have opted for another (USB) PIC programmer. I would have and would not have had to construct a Serial - 10 pin header cable for my ASUS P5B Motherboard. With that said, however, my K8048 is now working fine and I can read from & write to the PIC without a hitch.
The only deviation I have made from the Velleman instructions, is regarding the PSU. Instead of using a 15.2V un-regulated PSU, I am currently using a ‘reclaimed’ ATX PC power supply. This PC power supply has pin 14 (Green wire in 20 pin plug - PS_ON…found to the left of the latching tag when looking at the pins) shorted to pin 13 or 15 (Black wire in 20 pin plug - Ground…found either side of the Green wire) This gives a 12V regulated supply using the Yellow wires for +12V and the Black wires for Ground. Some PSU’s need a load placed upon them by connecting a 10 Watt, 10 Ohm load resistor across the 5V rail (Red wire to Black wire). Others simply require a typical PC cooler fan, which is sufficient when connected to one of the Molex connectors. I Short the Green/Black pins and connect supply to the K8048/V111 BEFORE switching the PSU on.
The Velleman instructions request that an un-regulated, approved 15V PSU is used. I chose to use what I had at hand and it worked for me.
You are free to make whatever choices you wish. If you choose to ignore the warnings on a PSU, or other circuits that implicitly state “No user-serviceable parts inside”, you do so at your own risk. Capacitors in power supplies, cameras, TV’s and other electrical goods that display similar warnings, do so for a good reason…they can be lethal if handled improperly…even if the power lead has been removed many months ago.
Disclaimer
I will not accept any responsibility for any injuries which may occur to any person adhering, or failing to adhere to any indicated warning on any apparatus that they are, or are not trained to operate on, with regard to the scope of this above text.
Regards,
Mickster.