Help finding a small and low cost programable logic IC.

[zapta]

I am looking for a programmable logic IC (FPGA, PLD, CPLD, etc) for a hobby project. Any suggestions will be greatly appreciated.

1. Runs on 3.3v.
2. Does not require additional ICs (LDOs, FLASH, etc).
3. Contains the non volatile memory (vs soft programming on boot).
3. Has an internal clock generator.
4. Free design tools.
5. Low cost programmer.
6. Low cost IC, and available in unit quantities.
7. Preference for a small package with a few I/O pins.
8. Logic complexity is minimal.
9. Security and code protection not an issue.
10. OTP is also OK.
11. Power consumption is not an issue.

Alternatively I could use a fast MCU, with a tiny program, but it needs to have a fast clock, e.g. 100+ MHZ. The RP2040 could be a good fit, especially with its PIO, but it requires an external flash.

[ataradov]

What is "Logic complexity is minimal"? How minimal? You need to provide at least an idea of what that logic would be doing.

I'm personally a fan of MachXO2 FPGAs. HC series runs from a single voltage and they have internal flash. They are available down to QFN32 packages.

[zapta]

What is "Logic complexity is minimal"? How minimal? You need to provide at least an idea of what that logic would be doing.

I'm personally a fan of MachXO2 FPGAs. HC series runs from a single voltage and they have internal flash. They are available down to QFN32 packages.

I don't know how to quantify it but really simple, to a point that every FPGA should be able to handle the complexity.

As for the MachX02, are you referring to these?  https://www.latticesemi.com/~/media/LatticeSemi/Documents/DataSheets/MachXO23/MachXO2FamilyDataSheet.pdf

One of the requirements is to have an internal clock generators (the higher the better, e.g. preferably > 20Mhz). Looking at table 1-1, the  XO2-256 XO2-640, do not have PLLs. Does it mean that they don't have generators? What about the ones with PLLs such as XO2-1200 (32 QFN), does this imply that they have a clock generator?

Also, what solftware and what low cost programmer can I use to design and program respectivly?

[ataradov]

One of the requirements is to have an internal clock generators (the higher the better, e.g. preferably > 20Mhz). Looking at table 1-1, the  XO2-256 XO2-640, do not have PLLs. Does it mean that they don't have generators? What about the ones with PLLs such as XO2-1200 (32 QFN), does this imply that they have a clock generator?"

Read "On-chip Oscillator" section. It has internal oscillator that is configurable from ~2 MHz to 133 MHz.

Also, what solftware and what low cost programmer can I use to design and program respectivly?

Lattice Diamond for the software and some cheap knock-off programmer from aliexpress. This one https://www.aliexpress.us/item/3256802957528698.html or any other version, they are all basically the same.

And if you just want programming without any advanced debug features (not that you will get many on a low end device anyway), then you can use any hardware supported by OpenOCD and OpenOCD. This can be as cheap as $5 for Pi Pico.

[zapta]

Thanks Alex. The internal oscilator is exactly what I need, so since PLL is not needed I can go with this one https://www.digikey.com/en/products/detail/lattice-semiconductor-corporation/LCMXO2-256HC-4SG32C/3232671

I presume that the programmer is in circuit which is also good.

Do you happen to have a schematic of a simple breadboard that shows the basic connections, power, ground, JTAG, and anything else that is needed to support this FPGA?

[ataradov]

Here is a breakout board for the 100-pin version https://github.com/ataradov/breakout-boards/blob/master/lcmxo256c/lcmxo256c_bb.pdf.

Although this one will be closer https://github.com/ataradov/breakout-boards/blob/master/lcmxo2-2000hc/lcmxo2-2000hc_bb.pdf .  The first one is for a MachXO without 2.

[zapta]

Thanks Alex. This is very useful. It matches very well all my requirements, and I think I have enough to continue.

Also found an open source breakout board a few years ago. TinyFPGA AX1. 

https://www.crowdsupply.com/tinyfpga/tinyfpga-ax-bx#products

https://github.com/tinyfpga/TinyFPGA-A-Series

[PCB.Wiz]

I am looking for a programmable logic IC (FPGA, PLD, CPLD, etc) for a hobby project. Any suggestions will be greatly appreciated.

1. Runs on 3.3v.
2. Does not require additional ICs (LDOs, FLASH, etc).
3. Contains the non volatile memory (vs soft programming on boot).
3. Has an internal clock generator.
4. Free design tools.
5. Low cost programmer.
6. Low cost IC, and available in unit quantities.
7. Preference for a small package with a few I/O pins.
8. Logic complexity is minimal.
9. Security and code protection not an issue.
10. OTP is also OK.
11. Power consumption is not an issue.

There are also GreenPAK Silego (now renesas) parts.

https://www.mouser.com/c/semiconductors/programmable-logic-ics/spld-simple-programmable-logic-devices/?m=Renesas%20Electronics

Their older smaller ones are OTP and new larger ones are EEPROM.  i2c program.
These are minimal macrocell/register parts, not super fast.

Renesas have also made press release noises a while ago, (17 Nov 2021 ) about ForgeFPGA ( starting SLG47910 in QFN24?) which seems a long time coming ?
No prices or stock showing ? Some app notes appear early 2023.

[ataradov]

Those SPLD devices are really strange. They have a ton of families with minimal differences. Sometimes it is hard to even tell what the difference is. And then there is no superset device that actually has enough logic to do something useful. They seem to be programmable devices, but the only things you can program are things that would have been implemented in a hard logic anyway.

The only advantage is that they publish full register map and don't need tools to configure.

And the ForgeFPGA are vaporware.

[zapta]

Looks very interesting. For example, the one below. A pile of assorted analog and digital functionality at a very good price. Do you know what tools they provide to design with them? I wonder what abstraction the tools provide.

https://www.mouser.com/ProductDetail/Renesas-Dialog/SLG46824V?qs=%252B6g0mu59x7IaPPlOrptPew%3D%3D

EDIT: The I2C programming is a plus because they can be updated by the MCU and I presume that the programming data is not too large.

EDIT: I think this is the design software. Very interesting. https://www.renesas.com/us/en/software-tool/go-configure-software-hub#overview

[SiliconWizard]

I'm personally a fan of MachXO2 FPGAs. HC series runs from a single voltage and they have internal flash. They are available down to QFN32 packages.

I second that. Another benefit of the internal flash is the 'very' fast startup time (at least compared to anything using an external flash chip).

[brucehoult]

Thanks Alex. This is very useful. It matches very well all my requirements, and I think I have enough to continue.

100 pins!!

What happened to "7. Preference for a small package with a few I/O pins." ?

idk, maybe 100 pins is small for an FPGA but it's huge for a microcontroller!

[iMo]

I messed a lot with the iCE40UP5k, it works nice.. Latest exercise I did - running a risc-v with 128kB internal spram memory (plus 15kB of internal bram). Two free dev chains, btw.
Small package, internal oscillator, low cost programmer (ie the FT232H).

[ataradov]

100 pins!!

We are discussing 32-pin version here.

[ataradov]

Looks very interesting. For example, the one below. A pile of assorted analog and digital functionality at a very good price.

If you looks closer, it is not a whole lot of logic. There is barely anything useful you can do with it.

[zapta]

Thanks Alex. This is very useful. It matches very well all my requirements, and I think I have enough to continue.

100 pins!!

What happened to "7. Preference for a small package with a few I/O pins." ?

idk, maybe 100 pins is small for an FPGA but it's huge for a microcontroller!

32 pins, 5x5mm.  Small enough and I can be soldered by hobbyists.

https://www.digikey.com/en/products/detail/lattice-semiconductor-corporation/LCMXO2-256HC-4SG32C/3232671

[PCB.Wiz]

...
EDIT: The I2C programming is a plus because they can be updated by the MCU and I presume that the programming data is not too large.

Yes, they have many carefully placed muxes, so there are limits on what can be connected to what.

The reprogrammable parts report this very small config memory  :

The SLG46824 provides 2,048 bits of Serial Electrically Erasable Memory internally organized as 16 pages of 16 bytes. The
protection settings of the device can be made permanent if desired.

first 2k bits are RAM loading, for development, second 2k bits are the NVM.

For comparison, if I check SPLDs, which have a more cross-point design,  a 16v8 has ~ 2k fuse bits, a 22V10 has ~6k and a ATF750 has ~14k, and ATF1502 (32 macrocells, 44 pins) has  ~17k

[PCB.Wiz]

32 pins, 5x5mm.  Small enough and I can be soldered by hobbyists.

https://www.digikey.com/en/products/detail/lattice-semiconductor-corporation/LCMXO2-256HC-4SG32C/3232671

Yes, and lattice also do a 1200 part in QFN32 too.  I've not checked if they are pin compatible.
LCMXO2-1200HC-6SG32C

[ataradov]

I would really like to see a practical thing done with Dialog SPLDs that is not power supply sequencing, which is what they are basically designed for. I may be lacking imagination, but they seem to be so limited.

[zapta]

I installed the design software. It's graphical design, similar to labview.  Looking at youtube for example, there is no much GreenPak related content that is not from Renesas. Not sure how widely it's used.

https://www.renesas.com/us/en/software-tool/go-configure-software-hub#overview

EDIT: The GreenPak serial debugger / programmer, is not available.  https://www.digikey.com/en/products/detail/renesas-electronics-corporation/SLG4DVKGSD/16254311?s=N4IgTCBcDaIOICcCmSB2AFAggaQAQGUkEBLAQwBtcARJAIwFcBzRokAXQF8g

[ataradov]

GreenPak is a trademark from Silego, which was acquired by Dialog, which was acquired by Renesas just a couple years ago. So, majority of stuff you see is still from Dialog.

I personally have never seen them used in any real product. I assume they go into some obscure server motherboards or something like this.

Their stats on use numbers are also convoluted, since "GreenPAK" applies to a wide rage of products, and SPLDs are just a minor subset of them. I expect fixed function devices to be more popular here.

I've got a few devices, since I like the idea of having a register map, so I will make a breakout board and try it out. But I really don't see practical applications for that. May be playing with them a bit will inspire something.

I would really like to see ForgeFPGA become real. They actually look interesting.

[zapta]

I couldn't find their serial debugger/programmer.  https://www.digikey.com/en/products/detail/renesas-electronics-corporation/SLG4DVKGSD/16254311?s=N4IgTCBcDaIOICcCmSB2AFAggaQAQGUkEBLAQwBtcARJAIwFcBzRokAXQF8g

I guess that straightforward I2C programming will also work but no integration with the development environment for debugging.

[ataradov]

I'm not sure how useful the debugger would be. You can read all the states of everything over I2C, so you can do some manual debugging, but I'd expect it to be easy enough to configure without needing to debug.

Sure, it is 2K bits, but a lot of them end up being unused, since they represent all possible multiplexing options. It does not seem to be particularly more complicated than a typical clock tree configuration in a high-end MCU.

In any case, the only reason I personally even remotely interested in them is the open documentation and ability to configure them without tools. So, I have not even tried to look at how their tools work.

[zapta]

I will make a breakout board and try it out. But I really don't see practical applications for that. May be playing with them a bit will inspire something.

They have here hundreds of samples designs, each with an application note and the design file.

https://www.renesas.com/us/en/products/programmable-mixed-signal-asic-ip-products/greenpak-programmable-mixed-signal-products/greenpak-applications#documents

Here is one example, definitly not just power supply sequencing related.

https://www.renesas.com/us/en/document/apn/cm-351-true-white-noise-generator-pink-and-brown-noise-outputs?r=1570646

[ataradov]

I meant practical designs. An actual consumer product where engineering decision was made that this device is better than other options.

I looked though some of those appnotes and more than ever I'm confused by the variety of the devices with limited set of functional units. There is an appnode of 8-bit I2C ADC that had to use two SPLDs because one had ADC and another had necessary comms. There is no way this is practical in a real commercial application.

Most of that stuff can be done with MCUs. SPLDs are 30 cents in quantity, so this is a huge plus over MCUs (especially if we only consider western brands).