47 lines
1.5 KiB
Markdown
47 lines
1.5 KiB
Markdown
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# spi Frequency
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Set the Serial Peripheral Interface (SPI) clock frequency.
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```sig
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pins.spiFrequency(1000000);
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```
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The @boardname@ sets the rate of data transfer and control timing for a SPI connection. This data rate and timing signal is controlled by the **SCK** pin. The signal on this pin is _clocked_ using the frequency set for it.
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### ~ hint
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**Simulator**: This function needs real hardware to work with. It's not supported in the simulator.
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### ~
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The default clock frequency is 1 Mhz (10000000 Hz). You can set the frequency for the SPI connection to some other value if you need a different data rate.
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## Parameters
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* **frequency**: a [number](/types/number) to set as the frequency for SPI bus clock. This value is the number of clock changes per second (Hz).
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## Example
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Read the value of the _WHOAMI_ register from the device connected to the SPI bus. The chip select line is connected to pin **0** and the SPI signals use pins **P13**, **P14**, and **P15**.
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```blocks
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pins.digitalWritePin(DigitalPin.P0, 1);
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pins.spiPins(DigitalPin.P15, DigitalPin.P14, DigitalPin.P13);
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pins.spiFormat(8, 3);
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pins.spiFrequency(1000000);
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pins.digitalWritePin(DigitalPin.P0, 0);
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let command = pins.spiWrite(143);
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let whoami = pins.spiWrite(0);
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pins.digitalWritePin(DigitalPin.P0, 1);
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basic.showNumber(whoami);
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serial.writeLine("WHOAMI register value: " + whoami)
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```
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## See also
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[spi write](/reference/pins/spi-write),
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[spi pins](/reference/pins/spi-pins),
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[spi format](/reference/pins/spi-format)
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[SPI Programming](https://developer.mbed.org/handbook/SPI)
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