General > General Technical Chat

AMD acquires Xilinx

<< < (7/12) > >>

Bassman59:

--- Quote from: gnuarm on April 13, 2021, 02:01:01 pm ---
--- Quote from: langwadt on April 13, 2021, 01:27:26 pm ---
--- Quote from: NiHaoMike on April 13, 2021, 12:54:59 pm ---The cost of making ASICs using a modern process is high enough that the volume would have to be really large and/or the gate count very high to justify going that route instead of FPGAs. As an example, some very early Japanese market Prius used FPGAs (likely sharing many design elements with the RAV4 EV at the time), then they switched to ASICs since there was a huge cost savings. But lately, they're going back to FPGAs for their hybrid and fuel cell vehicles instead of designing new ASICs since modern FPGAs are a lot cheaper so going to ASICs would not save much.

--- End quote ---

--- End quote ---

I'm curious as to what in an EV requires an FPGA rather than an MCU or DSP?  The calculations are not so intense or high speed.  I am a big proponent of using FPGAs for such control applications, but most of the community does not agree with me.  Where did you read about this?
--- End quote ---

I have no way of knowing whether NiHaoMike's assertions are correct, but the one thing the FPGA gives over an MCU or DSP is flexibility. How many SPI peripherals do you need? The MCU has a limit. Maybe 8 on that NXP LPC55 thing with its FLEXCOMMs. In an FPGA? How many pins ya got?

It may very well be that those FPGAs in the car have an embedded processor doing processor-type stuff and they add on the exact peripherals needed.

gnuarm:

--- Quote from: Bassman59 on April 13, 2021, 03:46:57 pm ---
--- Quote from: gnuarm on April 13, 2021, 02:01:01 pm ---I'm curious as to what in an EV requires an FPGA rather than an MCU or DSP?  The calculations are not so intense or high speed.  I am a big proponent of using FPGAs for such control applications, but most of the community does not agree with me.  Where did you read about this?
--- End quote ---

I have no way of knowing whether NiHaoMike's assertions are correct, but the one thing the FPGA gives over an MCU or DSP is flexibility. How many SPI peripherals do you need? The MCU has a limit. Maybe 8 on that NXP LPC55 thing with its FLEXCOMMs. In an FPGA? How many pins ya got?

It may very well be that those FPGAs in the car have an embedded processor doing processor-type stuff and they add on the exact peripherals needed.

--- End quote ---

That's my point.  There is no use in idle speculation.  We might as well imagine they are designing with 7400 TTL or hand wired transistors.  I saw a computer built from transistors in high school.  Our electronics class was given one from the weather service.  A FF was a small board.  Our instructor showed us the soldering and pointed out that flaws we could not see would flunk it for military or space applications.  I believe it used a magnetic drum for main memory.  Much of the circuitry was likely just for timing the memory accesses. 

A car could do something similar since it has so many rotating parts.  lol  See where speculation gets us?

Wolfram:

--- Quote from: gnuarm on April 13, 2021, 02:01:01 pm ---
--- Quote from: langwadt on April 13, 2021, 01:27:26 pm ---
--- Quote from: NiHaoMike on April 13, 2021, 12:54:59 pm ---The cost of making ASICs using a modern process is high enough that the volume would have to be really large and/or the gate count very high to justify going that route instead of FPGAs. As an example, some very early Japanese market Prius used FPGAs (likely sharing many design elements with the RAV4 EV at the time), then they switched to ASICs since there was a huge cost savings. But lately, they're going back to FPGAs for their hybrid and fuel cell vehicles instead of designing new ASICs since modern FPGAs are a lot cheaper so going to ASICs would not save much.

--- End quote ---

--- End quote ---

I'm curious as to what in an EV requires an FPGA rather than an MCU or DSP?  The calculations are not so intense or high speed.  I am a big proponent of using FPGAs for such control applications, but most of the community does not agree with me.  Where did you read about this?


--- End quote ---

I can only speculate on the justification, but Tesla drive units I've taken apart have used FPGAs as part of the motor control. The big rear drive unit in the Model S uses an Actel/Microsemi ProASIC3 for example, along with a couple of TI motor control DSPs.

peter-h:
Most motor control today is 3 phase brushless stuff and most of it is done with fairly fast CPUs e.g. ARM32F. These have 1-2us conversion time 12-bit ADCs, 12 bit DACs, and are easily capable of doing this job to any level of sophistication.

The problem is that designers like job security and there is nothing better than an FPGA for that. Nobody can do anything with it once the original designer is gone :)

filssavi:

--- Quote from: peter-h on April 13, 2021, 09:22:36 pm ---Most motor control today is 3 phase brushless stuff and most of it is done with fairly fast CPUs e.g. ARM32F. These have 1-2us conversion time 12-bit ADCs, 12 bit DACs, and are easily capable of doing this job to any level of sophistication.

The problem is that designers like job security and there is nothing better than an FPGA for that. Nobody can do anything with it once the original designer is gone :)

--- End quote ---

That is as long as you are unsina a VSI inverter with standard modulation, or maybe a diode clamped NPC (if you chose the correct MCU) anything more than that and the PWM modulators/timers will not be sufficient anymore
Than you are forced to go to an FPGA  just to have enough of the right kind of PWM channels ( most STM32 while more than capable enough from a computational power perspective have only 1 “advanced” timer that does deadtime, complementary outputs etc.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod