SPI maple master - arduino slave

(2 posts) (2 voices)

superprp
Member

Hi!

I am trying to comunicate a maple with arduino throught SPI (due to I cant comunicate in I2C with maple as slave) and I have one doubt.
How it works if frecuency in MAPLE is 72Mhz and in arduino is 16Mhz? Could I modify this to use the 8Mhz clock in MAPLE x 2 to get 16Mhz? Because if not, following documentation it is like this:

MAPLE:

Values:

SPI_18MHZ = 0 -

18 MHz
SPI_9MHZ = 1 -

9 MHz
SPI_4_5MHZ = 2 -

4.5 MHz
SPI_2_25MHZ = 3 -

2.25 MHz
SPI_1_125MHZ = 4 -

1.125 MHz
SPI_562_500KHZ = 5 -

562.500 KHz
SPI_281_250KHZ = 6 -

281.250 KHz
SPI_140_625KHZ = 7 -

140.625 KHz

ARDUINO:

SPI_CLOCK_DIV2 = 8Mhz
SPI_CLOCK_DIV4 = 4Mhz
SPI_CLOCK_DIV8 = 2Mhz
SPI_CLOCK_DIV16 = 1Mhz
SPI_CLOCK_DIV32 = 500khz
SPI_CLOCK_DIV64 = 250KHz
SPI_CLOCK_DIV128 = 125Khz

Posted 2 years ago #
gbulmer
Moderator

superprp - it doesn't really matter what clock rate the two processors are running at.

Only one MCU provides the SPI clock, and the other is a slave, and hence the slave simply receives the master's clock.

So, the clock from the master must be slow enough for the slave, then the slave will clock data in and out of its shift register using the masters clock signal.

Also, you can get the communication working at slow speed, and then speed it up when everything is working.

Posted 2 years ago #

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