How to mesure current SPI transfer speed

Kevyn-Alexandre Paré

author

2011-01-07 18:51 UTC #0 lore raw

Hi,

What's the best way to calculate the current SPI transfer speed?

Right now I use something like that and transfer one spi_message with 1 spi_transfer of 100000 bytes and I do the math... I know that this is not accurate and was wondering if anyone have a better way?

struct timeval tv_before;
struct timeval tv_after;

do_gettimeofday(&tv_before);
    status = spi_sync(spike_dev.spi_device, &spike_ctl.msg);
do_gettimeofday(&tv_after);
    long elapsedTime = (tv_after.tv_usec - tv_before.tv_usec);

Thx

--
Kevyn-Alexandre Pare

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Jassi Brar

2011-01-08 02:16 UTC #1 lore raw

Quoted 9 lines · Kevyn-Alexandre Paré

Hi,
What's the best way to calculate the current SPI transfer speed?
Right now I use something like that and transfer one spi_message with 1 spi_transfer of 100000 bytes and I do the math... I know that this is not accurate and was wondering if anyone have a better way?

Quoted 7 lines

struct timeval tv_before;
struct timeval tv_after;
do_gettimeofday(&tv_before);
status = spi_sync(spike_dev.spi_device, &spike_ctl.msg); do_gettimeofday(&tv_after);
long elapsedTime = (tv_after.tv_usec - tv_before.tv_usec);

Transfer speed is tightly linked to MOSI/MISO bit rates. But the overall throughput would depend on the protocol that you run over SPI.

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Kevyn-Alexandre Paré

author

2011-01-10 20:25 UTC #3 lore raw

Quoted 14 lines · Jassi Brar

Quoted 12 lines · Kevyn-Alexandre Paré
Hi,
What's the best way to calculate the current SPI transfer speed?
Right now I use something like that and transfer one spi_message with 1 spi_transfer of 100000 bytes and I do the math... I know that this is not accurate and was wondering if anyone have a better way?
struct timeval tv_before;
struct timeval tv_after;

Quoted 8 lines

Quoted 4 lines
do_gettimeofday(&tv_before);
   status = spi_sync(spike_dev.spi_device, &spike_ctl.msg);
do_gettimeofday(&tv_after);
   long elapsedTime = (tv_after.tv_usec - tv_before.tv_usec);
Transfer speed is tightly linked to MOSI/MISO bit rates. But the overall throughput would depend on the protocol that you run over SPI.

Effectively, but how to monitor that I respect, for example, a requirement of 5Mbps with a chip... I'm already sending data at

#define SPI_BUS_SPEED 5000000
spi_device->max_speed_hz = SPI_BUS_SPEED;

So does this settings ensure it to always be at 5Mhz?

I will try to test it by settings it to higher speed to see what happen
ex: 48000000 (48Mhz)

Regards,

--
Kevyn-Alexandre Pare

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Gaining the trust of online customers is vital for the success of any company
that requires sensitive data to be transmitted over the Web. Learn how to
best implement a security strategy that keeps consumers' information secure and instills the confidence they need to proceed with transactions.
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Jassi Brar

2011-01-12 02:29 UTC #4 lore raw

Quoted 19 lines · Kevyn-Alexandre Paré

Quoted 10 lines
Quoted 10 lines
What's the best way to calculate the current SPI transfer speed?
Right now I use something like that and transfer one spi_message with 1 spi_transfer of 100000 bytes and I do the math... I know that this is not accurate and was wondering if anyone have a better way?
struct timeval tv_before;
struct timeval tv_after;
Quoted 8 lines
Quoted 4 lines
do_gettimeofday(&tv_before);
status = spi_sync(spike_dev.spi_device, &spike_ctl.msg); do_gettimeofday(&tv_after);
long elapsedTime = (tv_after.tv_usec - tv_before.tv_usec);
Transfer speed is tightly linked to MOSI/MISO bit rates. But the overall throughput would depend on the protocol that you run over SPI.

Quoted 7 lines

Effectively, but how to monitor that I respect, for example, a requirement of 5Mbps with a chip... I'm already sending data at
#define SPI_BUS_SPEED 5000000
spi_device->max_speed_hz = SPI_BUS_SPEED;
So does this settings ensure it to always be at 5Mhz?

Not always.
Your protocol driver can theoretically set any rate from
[0, SPI_BUS_SPEED]. And bits would be shifted in/out
at that rate whenever the protocol driver has some data to recv/send. Usually, streaming devices(like DMB) will have more or less the same throughput equal to the clock rate, but bulk devices (like MMC) may not.

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