 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : SC Micromite + Backpack NoGo
| Author | Message | ||||
OA47 Guru  Joined: 11/04/2012 Location: AustraliaPosts: 911 |
I threw together a Silicon Chip Micromite Plus 64 pin backpack on the weekend unfortunately it wont boot. I was wondering if any shedders could direct me as where I might look to ascertain my problem. Firstly I will admit that I have scrounged some components to complete the PCB. All 3.3 voltage points test ok. I have tested for shorts between pins on the PIC and USB connector. Have checked for shorts on all caps and metered the resistors. I am able to program and verify the PIC chip with Micromite_Plus_5.03.02.hex. The unit does not respond when powering up from USB (no search for driver) and no response from Tera-Term on the serial port when powered by an external 5V. Any help as to where to look next would be appreciated. Graeme |
||||
CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1985 |
is the reset circuit working OK? try tapping GND to the reset pin of the PIC through a 4K7 resistor |
||||
Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
What is the current consumption of the board? Remove the LCD if you have one - we are only interested in the current of the main board. Double check your crystal oscillator section, as programming the firmware does not use the crystal oscillator, so the HEX will download to the chip fine, but if the crystal oscillator is not running correctly, the code will not run. Current should be around 40mA-50mA or so. If you only have 10-15mA then the PIC32 is not running. MCLR MUST be pulled UP to Vcc, so double-check that it's resistor is in place. Without it, the core will not start. Smoke makes things work. When the smoke gets out, it stops! |
||||
Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3165 |
My bet is that something is wrong with your power supply - often a flaky power supply will let you program the chip but causes trouble when the chip runs at full speed and draws more current. Also, check the crystal and the capacitor connected to the Vcap pin. Geoff Geoff Graham - http://geoffg.net |
||||
| OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 911 |
@ CaptainBoing, No go with the reset. @ Grogs, I don't have a LCD connected. Current consumption is only 12mA. @ Geoff & Grogs, the Vcap I scrounged from a dead maximite board so should be ok. The 20Mhz crystal is one that I scrounged from a network card. It is very possible it isn't working or I have the wrong caps size. I may have to order a new one before I can progress. |
||||
| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
12mA is too low - I bet the PIC32 core is not running. I would replace the Vcap. I know you scrounged it, but you might have heat-damaged it in the process. MLC's can be unforgiving.... I understand why you scrounge parts, but I have to say at this point, that using brand-new parts on any build is really the only way you can guarantee that the parts are not the cause of the problems, or a contributory factor in any case. The problem with using scrounged parts, is that you can't guarantee that the scrounged parts are OK when you scrounge them. Brand new parts will 99.99% of the time be perfectly fine BECAUSE they are new. Smoke makes things work. When the smoke gets out, it stops! |
||||
| OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 911 |
@ Grogs, I hear what you are saying and I would advise any one else the same, BUT I am impatient some times and had all but 3 components needed to load the PCB and those components' cost would be heavily outweighed by the freight cost in ordering them. BTW the Vcap still measures 10.07 uF with the meter. Thankyou for your prompt replies Graeme |
||||
| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8592 |
Make sure the caps on the crystal are OK and the correct values - if you have 22nf instead of 22pf the crystal won't start |
||||
| SteveA Regular Member  Joined: 10/03/2017 Location: United KingdomPosts: 48 |
I've just built two of these. I'm just waiting for Q1 and Q2 to finish them. Both programmed OK, and powered via USB worked with a serial to USB converter. But neither would work via the USB socket on the pcb! After much head scratching and re-soldering, I found they wouldn't connect thru' a powered USB hub. Plug them straight into the PC and they work perfectly, no idea why! As well as Vdd, have you checked the earth pins 9,20,25,41 ? |
||||
| OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 911 |
I removed the 20Mhz Crystal and scrounged another from an Intel mainboard (Please forgive me Grogster  ) The crystal was attached as a SMD but I was pleasantly surprised to find that the legs were folded out and it could be mounted through hole. Unfortunately there was no change so I decided to remove the 22pF caps. The caps measured around 24pF but I changed them with another series of 20pF cap I had and VOILA every thing came to life.Thankyou all for your help and assistance and to quote a well known Aussie actor: "Now we can all get some sleep" All the best Graeme |
||||
| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9066 |
Well done.  I think the oscillator caps can be anywhere from about 18pF up to about 27pF - so long as they are both the same value. I have never had any problems with 22pF caps, and that is what I have always used.... Smoke makes things work. When the smoke gets out, it stops! |
||||
disco4now Guru Joined: 18/12/2014 Location: AustraliaPosts: 844 |
The and verify is not a good sign when you program with the MMBasic HEX. If it runs after its programed it changes some values, so a good one will actually fail the verify. Latest F4 Latest H7 |
||||
| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1985 |
yay! |
||||
| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2290 |
i believe this is only so with mplab and pickit3. using pic32prog (and either a pickit2 or one of the several variations of ascii ICSP adapter) the target pic32 is held in reset throughout the whole program-verify process. cheers, rob :-) |
||||
| SteveA Regular Member Joined: 10/03/2017 Location: United KingdomPosts: 48 |
Verify also fails with a genuine Microchip ICD3 using MPLAB IPE. Now I know why! |
||||
 Print this page |
