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Forum Index : Microcontroller and PC projects : Homebrew Maximite programming settings
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stuarts Senior Member  Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Geoff, as I was in the long queue to order a Maximite, as you know, I bit the bullet and ordered a board from batchpcb. Got 2 in the end. I assembled the first one and discovered after that there was a copper short on the board under the solder resist that shorted one of the crystal pins to Vdd. Even after cutting the short out, I see no evidence of the oscillator running. As I had a second board I ordered 2 more PIC32s from microchip and they arrived today. Just tonight I've assembled enough of it that I have usb for power, crystal, and all caps loaded. and necessary resistors. I programmed it and have no errors there. All verifies ok. When I power it on I get no power LED and no indication from my PC that it has seen a USB device. I am just wondering is there anything I need to do when programming it apart from select the programmer type in MPLAB, the device type and just load the hex file. Are there any settings that I have missed. Stuart Time is nature's way of keeping everything from happening all at once. |
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Geoffg Guru  Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
You should not have killed the chip just by shorting the crystal pins. The PIC32 is a tough little sod, I once (by accident) had one running on 5V and on another time I reversed the power polarity. With no damage in both cases. No power LED means that the firmware did not run. Do you have the xtal oscillator running? If that is not running it means that you don't have a working firmware loaded or there is no power. I guess that the programmer verified OK and did not report an error, in that case the chip must have power. You must start with the firmware that includes the bootloader (V2.1) available on my website. Everything after that are updates only (ie, they do not include the bootloader and are intended to be loaded by the bootloader). You load the firmware into MPLAB using the Import option then program as normal. When correctly programmed the chip will start running and turn on the power LED with just the xtal and decoupling caps. It does not matter if the USB, VGA, etc is connected or missing. So, check the power, xtal and decoupling caps - that is all it needs to run. Geoff Geoff Graham - http://geoffg.net |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Geoff, I have the rev 2.1 and that is what I have used. On the second one which is the one I am trying to get going, it has the crystal, the decoupling caps and the 3.3v regulator, processor and usb connector to provide the 5v. I figured that was as close to a minimum system as I could get for testing and troubleshooting. I can see that I have 8MHz at the crystal pins, but only about 300mv p-p. I'm not really sure what sort of level I should see there. The power led doesn't light and it is not recognised on the USB on the PC. My real question was what settings do I need in MPLAB or the standalone pickit3 programmer software to do the programming. I have assumed that all I need is to set the device type, and import the hex file and program from there. But as Benny Hill told me many years ago, to assume makes an ass out of u amd me. Any guidance would be gratefully accepted. Stuart Time is nature's way of keeping everything from happening all at once. |
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donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Sorry Stuart, I saw your name and even the picture, but didn't realize it was someone I have known for 37 million years, well not until you rang tonight. We even worked together for many years, and Stuart is someone who knows electronics as he is an engineer with a large company everyone knows, and I can't even speel injunerr. So he shouldn't be having this trouble. I couldn't throw any light on it, but I have been able to offer him a get out of jail card. Cheers Don... https://www.dontronics.com |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
Hi Stuart, 300mV sounds low - I cannot remember what I normally see but I think that it should be at least a volt or two. Can anyone with an oscilloscope check theirs and tell Stuart? Detailed programming sequence: 1. Start MPLAB. 2. Make sure no other project/workspace is open by selecting File -> Close Workspace from the toolbar. 3. Select the target device by selecting Configure -> Select Device. 4. Open the Configuration Bits dialog by selecting Configure -> Configuration Bits from the toolbar. Make sure the checkbox labelled 'Configuration bits set in code' is SET. 5. Select the programmer and enable it. 6. Import the HEX file by selecting File -> Import. Importing the hex BEFORE selecting the programmer or target device will cause the HEX file to be cleared from memory, so it is important to do it in the order shown here. 7. Program the device. BTW. I am about to set off on another leg of my journey and will be away from civilisation (ie, Internet) for 10 days or so. So please forgive if I do not reply straight away. Geoff Geoff Graham - http://geoffg.net |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
With respect to ground I see about 3.3 volts on one side of the crystal and about 2.9 on the other. Just wondering if Stuart has the cro probe switched to X10 and not allowed for it on his readings. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Thanks Glenn. you were right, I did have the probe set to 10x, I thought I had reset it. I'll have another go at programming it as pre Geoff's instructions, but I am pretty sure I've done it in the order previously. Fingers crossed. Time is nature's way of keeping everything from happening all at once. |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Geoff, thanks for your help, make sure you enjoy that outback properly, forget that civilisation and the internet exist.. Time is nature's way of keeping everything from happening all at once. |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Does that mean you got it working Stuart? Cheers Don... https://www.dontronics.com |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
I know I am being paranoid and I've downloaded the Maximite 2.1 including bootloader several times. Can anyone tell me what the checksum shown in MPLAB is after loading the hex file? Mine shows 0xf99ee87c. Time is nature's way of keeping everything from happening all at once. |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
unfortunately no Don Time is nature's way of keeping everything from happening all at once. |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
OK, I may be able to assist you tomorrow, maybe Monday. Cheers Don... https://www.dontronics.com |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Well after many hours of troubleshooting over several days I finally found a workaround for why mine weren't booting. While probing voltages this afternoon, I accidentally shorted pin 56 (Vcore) to pin 57 (Vdd). the Maximite immediately booted. I found that this worked reliably on both of my units. I still dont really know why. The workaround that I have come up with is to add a 22uF tantalum cap from Vcore to Vdd. This just briefly holds Vcore high when power is applied. I now have 2 working Maximites and I'm too mentally drained to do much with them. Stuart. Time is nature's way of keeping everything from happening all at once. |
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jebz Regular Member  Joined: 13/06/2011 Location: AustraliaPosts: 79 |
Some people had trouble programming the WIB dsPIC33 when Vcap was not installed. On the Maximite it's C5 connected to pin 56. This might be worth checking. |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Jebz, I've checked both C5 and C12 on both units and replaced them. Also checked continuity between all PIC pins and the connected components. I dont know who else has built up a Maximite using the boards ordered from BatchPCB. As far as I can tell, they seem to conform to the curcuit diagram. All I know is I had the same problem on both boards and the workaround has worked on both of them. The addition of the extra cap from Vcap to Vdd seems to have fixed the issue. I know I shouldn't need it but I dont see another solution at this point. Stuart Time is nature's way of keeping everything from happening all at once. |
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trippyben Regular Member Joined: 26/06/2011 Location: AustraliaPosts: 91 |
Thanks for posting this, had the same problem with my own home brew Maximite and found the solution here!!! I used a 10uF 25V Tant for C5 in lieu of the 10uF 16V tant specified in the BOM. With the extra cap (33uF electro in my case) between Vcore and Vdd the torublesome beast springs to life! According to the microchip datasheet, the ESR of the Vcore cap must be less than 1ohm, I can only guess that the higher voltage rated tant is a little bit higher in ESR causing the problem? |
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| stuarts Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 199 |
Trippyben, I'm glad you noticed this, and also glad that my workaround helped you. I only discovered it by accident being born with 10 thumbs and slipping and shorting the Vcore pin to Vdd and having the Maximite burst into life. I might just have to go find the right cap now and see if that solves the problem. I'm pretty sure mine were 25v as well. Stuart Time is nature's way of keeping everything from happening all at once. |
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| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Maxiteers, I'll add this snippet to my hardware page for the benefit of others. http://www.themaximitecomputer.com/maximite-control/ Cheers Don... https://www.dontronics.com |
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| PeterR Newbie  Joined: 28/06/2011 Location: Posts: 2 |
Had the same problem. Built 2 homebrew maximites using smd adapters from Futurlec and both failed to run Maximite firmware. The frustrating thing was that i was able to successsfully compile and run a "hello world" program using the external 8meg Xtal with system clock running at 80MHz. Tried your trick Stuart and both Maximites burst into life. Many thanks for your serendipity. Rather than placing another cap between Vdd and Vcore I decided to try a number of tantalun caps for C5 from my junk box. Results: 10uF 25V NOK 15uF 35V OK 22uF 16V OK 22uF 35V OK 22uF 16V NOK 22uF 16V OK The last 2 caps were from the same manufacturer! I guess the conclusion is that some work and some don't, no obvious pattern here. I wish I could test the ESR of these caps but I don't have the gear. Peter |
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| aargee Senior Member Joined: 21/08/2008 Location: AustraliaPosts: 255 |
Yes, I have replaced the 10uF/25V tantalum capacitor (and the 22uF 'kickstart' cap mod) with a 10uF/35V SMD chip type tantalum and it all works fine. The SMD cap just soldered straight onto the pads of the 10uF cap was. It's ESR was 0.4 Ohm. My thoughts are that the larger voltage rated caps will probably be better due to their lower ESR. (Even though my original measured 0.3 Ohm!) Go figure?!? I have this habit of salvaging old boards from our e-waste area at work and stripping off the 'good stuff', so I've ended up with a nice supply of SMD bits. Board + Hot air gun = lots of tiny bits all over the garage floor. - Rob. For crying out loud, all I wanted to do was flash this blasted LED. |
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