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Forum Index : Microcontroller and PC projects : 170 core + RTC and Fram on 28pin DIP
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Zonker Guru  Joined: 18/08/2012 Location: United StatesPosts: 767 |
Good Morning Gent's... Just wanted to get you guys a peek at the new board I have been working on... It uses the FM32L278 Processor Companion IC for RTC and 32k of Fram storage and has the FTDI USB IC for console interface. I have been laying out the PCB and it looks like it will all fit on a standard 28 pin DIP socket sized board.!! The layout is almost done and I will post it when finished... I just wanted a little feedback from the group to see if things check out ok... 2014-09-30_093356_schematic.pdf 2014-09-30_093641_PCB.pdf Finishing up shouldn't take to much longer... |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Hi Zonker, Looks better every time I see it! One thing - the single LED on the FTDI chip is labelled TxRx - how does that work? Also, have you decided yet on the FRAM (i.e. the '6' or the '8'). Should be a lot of interest in this excellent 'logger' MicroMite Module 
WW |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Morning Wiz.. The FTDI chip can be reprogramed with the FTDI utility software to use the extra I/O pin as a Rx-Tx LED... So I stuck one on.. The Fram will be 32k x 8 and will be the FM32L278 chip.. I hope there is enough room for the reset switch..! I should be done with the layout stuff by the weekend... |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
The reset switch I was meaning in our 'chat' was one like this . Just need to find a main-stream supplier. . . . WW |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Looks nice and compact! Maybe connect some FT232 lines to the PGC/PGD (maybe with a small jumper) so that you can program the 170 with a PC using the USB. Details here
Microblocks. Build with logic. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
Coming along nicely! 
Is it skinny DIL or wide DIL? Smoke makes things work. When the smoke gets out, it stops! |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Well, I wish it was a skinny (300)... But it's a wide... (600)... Still, this will be the most dense SMD board I have ever done... I hope everyone will find it useful.!! @TZ.. Do you mean connect up the RTS-CTS control lines to the prog interface..? If so, how could we restart the PIC into programming mode..? I am using the FT234XD part in the DFN12 package for the size. I got most of it to fit just behind the USB connector. It doesn't have extra I/O lines except for the one controlling the Rx-Tx LED... |
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Lou Senior Member  Joined: 01/02/2014 Location: United StatesPosts: 229 |
Way to go Zonker, I can't wait to build some of those - except for the DFN chip. I see you're using the 28 pin SSOP part I've been wanting to play with. Lou Microcontrollers - the other white meat |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Good evening Gent's... Ok, Finished routing the board... Next, got to do a cleanup pass and check for manufacturability per Itead speck... Also had just enough room to add a "heat spreader" area around the V-reg parts... So, the user gets a reg and the MPU gets it's own v-reg... Any feedback out there would be good..! 2014-10-03_020744_Top.pdf 2014-10-03_020811_Bottom.pdf Getting there..!!  |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9588 |
Looks good.
Your track clearances must be about as tight as you can make them in places! Smoke makes things work. When the smoke gets out, it stops! |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Hi Zonker, this is very cool. I would like to get one or two once finished. Should prove to be quite useful. I have been checking out the reflow oven thing for a while and it seems like this would be a great unit to try it with. |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Revisiting this thread due to all the talk about the FRAM device. I did a bit of googling to find out some info on the Fram being used on the Zonkermite board. It seems from what I can find that the FM32L278 unit is obsolete and replaced with FM31256-G by cypress. Looking at both, they seem identical, but that was just a quick look. At least there is availability. 100 trillion read/writes and 151-year data retention - This could make a cool time capsule.... |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Yep... Lou picked up on this... I have yet to update the part number, but we are planning on using the new version of the part, although, as of now, the older part still shows as stock at Digikey.. We are back to 10 hour days at work again, so getting time on this is getting tighter.. Currently, I am trying to move things around a little to make "hand building" the board easer... It's still going to be quite a challenge..!! I reduced the size of the MPU tracks to 0.007 to get a little more space between them... I also tried printing the design and placing the SSOP MPU to check the spacing around it... I decided to bump the regulators over a little to give the builders enough space to solder the surrounding passive parts around it. Also, I need to add one more .1uf cap for the Fram part... It should be easy because it's on the bottom side where there is more room. I think a little more time spent now will help make the finished unit easier to produce... I will post an update of things as soon as I can. All feedback on this project is welcome.. If anything doesn't look right for any reason, please let me know..!! Trying to "get-er" done... Zonk |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Hi Zonker, I don't know why I did not pick up on this earlier, but it appears that you have parts on both sides of the board. No big deal, but how do you use reflow with something like this. Do they glue the parts on to the board first? Either way, can't wait till they come out. Looks like a great little Zonkermite, with all the right stuff. |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Ok... It's getin close Finished the cleanup, added the .1uf cap for the Fram IC, and added a Vbat holdup cap too... (was Lou's idea) Any last minute changes out there..? 2014-10-12_051511_DIP-600-28_Scematic.pdf 2014-10-12_051537_DIP-600-28_TOP.pdf 2014-10-12_051607_DIP-600-28_BOTTOM.pdf Any feedback welcome..! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Hi Zonker, After looking at the schematic I have one request: PLEASE can you squeeze in a reset switch? It is such a useful thing to have onboard when developing. I know you can ground out Pin 1 on the ICSP connector BUT this is from the voice of experience of having built well over 200 units - it really is the most invaluable thing to have on-board
I will now look at the board lay-outs to see if I'm asking the 'impossible' 
WW |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Oops... Forgot about the reset SW... We will be giving up on the heat spreader area for this I think.. I will have a poke at Digikey... |
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jman Guru Joined: 12/06/2011 Location: New ZealandPosts: 711 |
Hi Zonker In your circuit diagram you have the VBak pin of the Fram on the 28 pin breakout connector is there a reason for this to a battery maybe ?. If you want to use a cap for Vbak 10uf is possibly going to be a little low. I have a 5.5v .5F connected to mine and that seems to work fine. Regards Jman |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Hey Jman.. Lou suggested a cap on the pin to hold up the Vbat source just long enough to transfer the preset "sleeping" module to a new habitat.. That was the idea anyway... I had just enough room on the backside to stuff in another .1uf cap and the 10uf holdup cap... The outside pin (20) is made to feed the RTC from a battery or super-cap of the users choice... Just got back from church and doing lunch.. Now off to find a tiny reset switch... Edit: Ok, after looking at a few, I decided on this one from Digi-Key (679-2400-ND) Will get busy creating the library part... hope it fits ok... |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
Link here as above link didn't work for me. I have used this one before - but, isn't it worth sourcing a smaller one? If you struggle to fit this part then let me know and I will look for a 'tiny' switch (i.e. the microscopic type used in mobile phones). WW |
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