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Linux boot time on the MityArm1808F

Added by Alex Kucherov about 11 years ago

Hello,

I'm new to ARM software development so please bare with me.

Some background on the project:
I'm working on a data logger project based on the MityArm1808F (currently using the Industrial IO Development Kit). My plan is to transfer the ADC outputs to the on board FPGA, do a bit of processing and then send the information to the AM1808 processor which will write the data to an SD card (we are developing a custom board which will carry the ADC,SD card and the MityArm).
The ADC data throughput will probably be higher than the SD maximal write speed, so I plan to use the MityArm's on board RAM memory as a buffer.

The problem:
A very important requirement for the project is to start the data sampling processs immediately after power is applied to the circuit (by "immediately" I mean no longer than 200ms).

So my questions are:

1) What is the typical boot time for linux(and the FPGA image)on the MityArm1808F?
2) Is it possible to achieve such a fast start up time using the MityArm's linux OS?
3) If not, is it possible to bypass the linux OS and program the ARM processor directly?

Thank you in advance,
Alex


Replies (4)

RE: Linux boot time on the MityArm1808F - Added by Alex Kucherov about 11 years ago

English is not my first language so please BEAR with me. :)

RE: Linux boot time on the MityArm1808F - Added by Michael Williamson about 11 years ago

Hello Alex,

We have not tried to much to get the boot times down to the levels that you are requiring. Keep in mind that the boot time of a "stock" implementation also includes the UBL load time (User Boot Loader, loaded from SPI, configures mDDR2 RAM) and the u-Boot time (also loaded from SPI). Those load times are certainly less than 200 ms but are non-zero.

Your questions:

1) I think the stock linux image, which has a lot of stuff turned on that you may not need, is on the order of 14-20 seconds. So this is not a good starting point.

2) I have seen (google will probably find it) folks claim to have tuned linux on the L138 (same as 1808) to start within 100 ms. But, they had to do a fair amount of tweaking and disabling of features, etc., to get there from here. (E.G., disable udev, disable all features you don't need, etc.). I am not confident that meeting your timeline with linux will be easy without a fair amount of investment of time / effort.

3) There is an option for a "bare-metal" ARM library (no Operating System) image called "starterware" that might get you what you need. It has some support code for most of the peripherals but as you can imagine requires a fair amount of brute force and understanding of deep embedded programming. We have had a couple of customers use this approach with success. See TI's website (probably find it with google, if not let me know and I can refer you to a link).

The SD card generally requires some negotiation on start up (a slower speed set of transfers prior to the faster speed), so you will likely have to buffer initially until the SD card can be configured.

-Mike

RE: Linux boot time on the MityArm1808F - Added by Alex Kucherov about 11 years ago

Thank you for quick response.

It seems that StarterWare is a feasible option.

If I understand correctly, StarterWare will create an image that will be loaded to the NOR flash memory and replace (or not?) the linux kernel. U-Boot will then be configured to load the StarterWare image and not the linux one. Is this correct?

Will I be able to load the StarterWare and FPGA images using the Industrial IO Development Kit or is a JTAG emulator necessary?

Thanks again,
Alex

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