3 ms·

It's a good question. A lot of FPGA projects I see (including some real life products I've looked into recently) don't really need an FPGA. One I was asked to e

It's a good question. A lot of FPGA projects I see (including some real life products I've looked into recently) don't really need an FPGA. One I was asked to evaluate recently could easily have been done with a microcontroller with PWM outputs. The frequencies involved were well under 40MHz. Yes, there were a couple of multiplications going on in the FPGA, but there those could've been easily handled by a micorcontroller. An RP2040 would've sufficed instead of what they had - a microcontroller + an FPGA.

azonenberg 2y ago
The projects in question include things like a 48 port gigabit Ethernet switch with packet datapath in the FPGA, and dual 10/25G SFP28 uplinks. You're not doing that on a MCU. Also higher end oscilloscope work (e.g. 10 Gsps 12-bit JESD204B) But a STM32 is more than sufficient for the management interface on both.
rvense 2y ago
I think a lot of people don't fully appreciate how fast a modern "microcontroller" is. That 'H735 is probably faster than every computer I had up to and including the iBook G4 I until early 2009.
- buescher 2y ago
  I keep running into that also. It's like the common mental model of a microcontroller froze around Y2K as a sort of headless VIC-20. I had an FAE, and a good one, from a major supplier tell me "you can't implement a filter" on a low-end micro that was roughly as powerful as an early nineties DSP.
  - rvense 2y ago
    Cortex-Ms, man. A lot of 'em you just give 3.3V and a couple of bypass caps, and GCC will use the single-cycle hardware MAC (for M4 and above) if you just write the straight-forward C code and you can put it on there in 600ms with DFU. I'm a hobbyist, not an embedded wizard, but it really seems *pretty* good compared to what I understand about the old days. (Like I like retro stuff and during COVID I bought an old DSP56k dev board with a book about the assembly language but oh boy, oh dear)
    - buescher 2y ago
      They're amazing. And - you can run a PC emulator on an ESP32. Sure, you need the fancy ram. OK. And then people will tell me an ESP32 can't do things that people definitely were doing on bare-bones PCs in the eighties.
15155 2y ago
Zynq 7010s are $2.50 and are a hell of a lot more chip than an RP2040. If you already have the design (or copy one of the 50 available), it's a good option when you don't want to fight the chip. PIO has extraordinarily sloppy timing (skew in all categories) compared to the cheapest and smallest FPGAs.
- azonenberg 2y ago
  Where are you getting them for $2.50?? The XC7Z010-1CLG225C is $74.83 at Digikey in qty 1. Checking sketchier places Win-Source has the CLG400 package for $22.20 and even the cheapest aliexpress seller wants $4.84 for something marked as a 7Z010 that may or may not be legit. Also "fight the chip" is pretty much the definition of what I did last time I did a zynq project. Just give me a plain FPGA and MCU with no wizards or GUIs or automatic code generation.
  - 15155 2y ago
    https://www.aliexpress.us/item/3256803970893483.html https://www.aliexpress.us/item/3256803970893483.html I've ordered trays (and they send the OEM tray) - unique barcodes, legit. > Just give me a plain FPGA and MCU with no wizards or GUIs or automatic code generation. You can pretty much cut out all of their tools and get a pure Yocto/Vivado TCL build for the bitstream for the 7 series Zynqs. Very low touch. Their IO planner (in the Vivado IP integrator) is somewhat necessary for complex peripheral scenarios and is one of the few things I ever use Xilinx GUI applications for anymore.
    - anyfoo 2y ago
      I don’t even find Vivado that bad, but maybe I have Stockholm syndrome. Or maybe it’s because I’m forced to use Intel Quartus right now and wish it was Vivado every time.
    - scottapotamas 2y ago
      I was interested to see, or at least what state they're in so I grabbed a couple. Might try to compare them against some genuine ones with CT and destructive inspection. On the chance they're half reasonable, thanks for the link.

azonenberg 2y ago

The projects in question include things like a 48 port gigabit Ethernet switch with packet datapath in the FPGA, and dual 10/25G SFP28 uplinks. You're not doing that on a MCU. Also higher end oscilloscope work (e.g. 10 Gsps 12-bit JESD204B) But a STM32 is more than sufficient for the management interface on both.

rvense 2y ago

I think a lot of people don't fully appreciate how fast a modern "microcontroller" is. That 'H735 is probably faster than every computer I had up to and including the iBook G4 I until early 2009.

buescher 2y ago
I keep running into that also. It's like the common mental model of a microcontroller froze around Y2K as a sort of headless VIC-20. I had an FAE, and a good one, from a major supplier tell me "you can't implement a filter" on a low-end micro that was roughly as powerful as an early nineties DSP.
- rvense 2y ago
  Cortex-Ms, man. A lot of 'em you just give 3.3V and a couple of bypass caps, and GCC will use the single-cycle hardware MAC (for M4 and above) if you just write the straight-forward C code and you can put it on there in 600ms with DFU. I'm a hobbyist, not an embedded wizard, but it really seems *pretty* good compared to what I understand about the old days. (Like I like retro stuff and during COVID I bought an old DSP56k dev board with a book about the assembly language but oh boy, oh dear)
  - buescher 2y ago
    They're amazing. And - you can run a PC emulator on an ESP32. Sure, you need the fancy ram. OK. And then people will tell me an ESP32 can't do things that people definitely were doing on bare-bones PCs in the eighties.

15155 2y ago

Zynq 7010s are $2.50 and are a hell of a lot more chip than an RP2040. If you already have the design (or copy one of the 50 available), it's a good option when you don't want to fight the chip. PIO has extraordinarily sloppy timing (skew in all categories) compared to the cheapest and smallest FPGAs.

azonenberg 2y ago
Where are you getting them for $2.50?? The XC7Z010-1CLG225C is $74.83 at Digikey in qty 1. Checking sketchier places Win-Source has the CLG400 package for $22.20 and even the cheapest aliexpress seller wants $4.84 for something marked as a 7Z010 that may or may not be legit. Also "fight the chip" is pretty much the definition of what I did last time I did a zynq project. Just give me a plain FPGA and MCU with no wizards or GUIs or automatic code generation.
- 15155 2y ago
  https://www.aliexpress.us/item/3256803970893483.html https://www.aliexpress.us/item/3256803970893483.html I've ordered trays (and they send the OEM tray) - unique barcodes, legit. > Just give me a plain FPGA and MCU with no wizards or GUIs or automatic code generation. You can pretty much cut out all of their tools and get a pure Yocto/Vivado TCL build for the bitstream for the 7 series Zynqs. Very low touch. Their IO planner (in the Vivado IP integrator) is somewhat necessary for complex peripheral scenarios and is one of the few things I ever use Xilinx GUI applications for anymore.
  - anyfoo 2y ago
    I don’t even find Vivado that bad, but maybe I have Stockholm syndrome. Or maybe it’s because I’m forced to use Intel Quartus right now and wish it was Vivado every time.
  - scottapotamas 2y ago
    I was interested to see, or at least what state they're in so I grabbed a couple. Might try to compare them against some genuine ones with CT and destructive inspection. On the chance they're half reasonable, thanks for the link.