Incorporating mojo in own board design

General discussion about the Mojo
markheloking
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Joined: May 12th, 2016, 12:32 pm

Incorporating mojo in own board design

Post by markheloking » May 12th, 2016, 12:40 pm

After having bought and playing a lot with the two mojo V3's, I want to incorporate the components on the board in designing for a project. I understand how to flash the bootloader to the Atmel chip. Is there anything I need to do to the fresh, factory Spartan-6 FPGA before everything works, or does that work out of the box in the mojo design?

A more simple way of asking the question: if on the mojo V3 I desolder the FPGA and solder on a new one, is there any flashing that needs doing or does it just work?

embmicro
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Re: Incorporating mojo in own board design

Post by embmicro » May 12th, 2016, 2:03 pm

There's nothing to do to the FPGA. The FPGA is RAM based so it's like a brand new chip every time power is applied (hence the external flash on the Mojo). We simply flash the AVR and run some tests (which also load the default LED program) when making the boards.

markheloking
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Joined: May 12th, 2016, 12:32 pm

Re: Incorporating mojo in own board design

Post by markheloking » May 13th, 2016, 5:54 am

Well that's good to hear (and as I suspected).

The eagle files on the website are missing some parts that are supposed to come from a "embeddedmicro.lbr" library. Is it possible to share this library? Otherwise I'll have to remake the footprints myself which will take quite a while.

Thank you very much for your support so far!

embmicro
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Re: Incorporating mojo in own board design

Post by embmicro » May 17th, 2016, 11:10 am

You can export all the parts in an Eagle board file to a library. Open the board/schematic and from the board editor run the ULP script "exp-lbrs.ulp". You then have the options to export all the board parts into a single library or split into the original libraries.

kxnz
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Joined: August 13th, 2016, 6:55 pm

Re: Incorporating mojo in own board design

Post by kxnz » August 13th, 2016, 7:14 pm

Hello,

Just another question regarding incorporating Mojo in my own board design -

I would like to make my own FPGA-based boards which use for example the FPGA as implemented on the Mojo board, with an atmega1280 and other components. I can just program the atmega1280 with ICSP, but I'd like to program the FPGAs on my own boards using the Mojo (V3). Is this feasible?

If I for example connected the MISO, MOSI, SCK and CS_FLASH pins of the Mojo board to the corresponding points on the flash memory of my target board, would I essentially be uploading the design to both boards simultaneously? Or would there be conflicts or other things that I'm missing. If that wouldn't work, are there any other options short of also making a separate programmer board which only duplicates the atmega32u4 section of the Mojo?

embmicro
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Re: Incorporating mojo in own board design

Post by embmicro » August 23rd, 2016, 4:29 pm

So the problem with this is that the AVR on the Mojo reads the flash and programs the Mojo every time power is applied and needs to be there. You could use the atmega1280 to do the same thing that the atmega32U4 is doing on the Mojo. As long as the serial commands are the same (you can use the Arduino source) it should work. You need to have a serial port connection to your computer though.

Also you can't really connect two flash chips in parallel because there are reads done to know when the flash chip is read for another write.

kxnz
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Joined: August 13th, 2016, 6:55 pm

Re: Incorporating mojo in own board design

Post by kxnz » September 30th, 2016, 6:35 pm

Thank you very much for your reply.

I made my board based on the Mojo V3 schematics (with the connections between the microcontroller and the FPGA/Flash made by a ribbon cable and a bunch of other stuff added), and I'm having trouble getting the 32u4 recognized by USB and getting the Mojo IDE to upload the firmware to it. I worry that my power arrangements or something about the USB connection isn't going correctly.

Could you please let me know what the fuse settings of the 32u4 are supposed to be? Is it right that the UVCC pin is not connected at all? All other schematics I have looked at with the 32u4 have that connected. I am able to upload code fine to the 32u4 via AVR ISP MkII, but the 32u4 is not recognized as a device, let alone a Mojo V3 when it is connected via USB.

Any help you could provide would be much appreciated.

markus
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Joined: October 3rd, 2016, 4:35 am

Re: Incorporating mojo in own board design

Post by markus » October 3rd, 2016, 6:50 am

I'm designing a board for a scientific project with the fpga interface being Mojo based. I've noticed that the flash chip on the Mojo V3 is by now more or less impossible to obtain, the manufacturer (Microchip) has marked it as 'obsolete'. Is there a compatible 3.3V 8x512k SPI flash chip / has it been decided which chip future Mojo's will use?

embmicro
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Re: Incorporating mojo in own board design

Post by embmicro » October 3rd, 2016, 12:38 pm

The current batch of Mojos use this flash chip http://www.digikey.com/product-detail/e ... ND/4824164

The latest AVR firmware supports either chip.

john smith
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Re: Incorporating mojo in own board design

Post by john smith » August 22nd, 2017, 10:07 pm

Hi
I would like to make my own FPGA-based boards which use for example the FPGA as implemented on the Mojo board, with an atmega1280 and other components. I can just program the atmega1280 with ICSP, but I'd like to program the FPGAs on my own boards using the Mojo (V3). Is this feasible?

If I for example connected the MISO, MOSI, SCK and CS_FLASH pins of the Mojo board to the corresponding points on the flash memory of my target board, would I essentially be uploading the design to both boards simultaneously? Or would there be conflicts or other things that I'm missing. If that wouldn't work, are there any other options short of also making a separate programmer board which only duplicates the atmega32u4 section of the Mojo?
best regards
john smith
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