topic Re: Acquisition FLEXIO/SD card in Kinetis Microcontrollers

Acquisition FLEXIO/SD card

lacouturepatric — Fri, 06 Sep 2019 13:33:48 GMT

I am working on a project of data acquisition. I must store data from ADC into a micro SD card. The data are from 1 bit to 4 bits (0/, sampled by a configured external clock from 16MHz to 32 MHz.

I found the micro Kinetis K80 that could be a solution thanks to the Flexio and the SD card controller. I have some questions.

Acquisition: Flexio,

1) What is the expected maximum input external Clock supported by the FlexIO peripheral for K80 (sampling)?

2) Is there any other NXP micro that can support higher input external Clock than K80?

Record: SD card controller

3) According to the SD card information, a micro SDXC SanDisk Extreme 128 Go can write data until 90 Mo/s. What could be the maximum writing speed that I can expect by using FatFs or blocks.

4) Which SD card would you recommend me to use for having the best writing performance.

Thank you,

Regards

Re: Acquisition FLEXIO/SD card

Alexis_A — Mon, 09 Sep 2019 20:47:45 GMT

Hi Lacouture,

I will try to answer your questions the best I can:

Acquisition: Flexio,

1) What is the expected maximum input external Clock supported by the FlexIO peripheral for K80 (sampling)?

In the reference manual mention that the maximum core clock can be used to supply the FlexIO.

2) Is there any other NXP micro that can support higher input external Clock than K80?

Other MCU that has the same features is the K28/K27, but it has the same core frequency. Other MCU that has this features is the i.MX RT 1050/1060, mybe you could take a look at it.

This peripheral is used to emulate other protocols like I2C, SPI or other protocols. I don't really understand the relation between this and the sampling in the ADC, are you going

Record: SD card controller

3) According to the SD card information, a micro SDXC SanDisk Extreme 128 Go can write data until 90 Mo/s. What could be the maximum writing speed that I can expect by using FatFs or blocks.

In the reference manual it mention the maximum data transfer is 200 Mbps for 4 lines, and 416 Mbps for 8 lines.

4) Which SD card would you recommend me to use for having the best writing performance.

Unforunately, NXP doesn't have a list or recommended SD to work with its harware but if the operating range is between the mentioned in the Table 56. SDHC full voltage range switching specifications it should be ok.

I hope this helps you.

Best Regards,

Alexis Andalon

Re: Acquisition FLEXIO/SD card

lacouturepatric — Thu, 12 Sep 2019 09:42:30 GMT

Hello Alexis,

Thank you very much for your answer.

Acquisition: Flexio,

I succeed to sample data at 21 MHz. For the test, I used an FPGA and the TWR-K80F150M. The clock and data were generated by an FPGA. The TWR-K80F150M capture the data (shifter) and the clk was used as Trigger. The software that I used was FLEXIO Camera example with the EDMA.

Do you think that 21 MHz is the upper limit for Flexio K80?

What is the expected maximum input external Clock supported by the FlexIO peripheral for i.MX RT 1050/1060?

Record: SD card controller

I think the 200 Mbps for 4 lines will not be enough for my application.

Do you have an example of MMC card using 8 parallel data than can accept a data transfer at 416 Mbps?

Can I used an SD card UHS 2 for having a data transfer at 416 Mbps.

Thank you,

Best Regards,

Patrice

Re: Acquisition FLEXIO/SD card

Alexis_A — Fri, 13 Sep 2019 17:37:22 GMT

Hi Lacouture,

Please check my answers below:

Do you think that 21 MHz is the upper limit for Flexio K80?

For K80, the limit is 25MHz.

What is the expected maximum input external Clock supported by the FlexIO peripheral for i.MX RT 1050/1060?

The operating clock is limited to 120MHz so it should expect a similar sample data rate than the K80.

Do you have an example of MMC card using 8 parallel data than can accept a data transfer at 416 Mbps?

Since this is for MMC it will not be the same since the SD Card only have 4 parallel lines.

Can I used an SD card UHS 2 for having a data transfer at 416 Mbps?

I think you could use it but the frequency at which the module work would not be enough to reach that speed.

For this the i.MX RT would be possible to use it since it has a better module than the K80.

Best Regards,

Alexis Andalon

Re: Acquisition FLEXIO/SD card

lacouturepatric — Wed, 02 Oct 2019 14:43:49 GMT

Ok, thank you very much for your help.

Regards,

Patrice Lacouture