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How many devices can be connected in SPI?
(Since only a single signal line needs to be tristated per slave, one typical standard logic chip that contains four tristate buffers with independent gate inputs can be used to interface up to four slave devices to an SPI bus.)
How do I connect two SPI devices?
Assuming you just want to connect two SPI slave devices to the SPI bus and use them in a mutually exclusive way under software control, with the Arduino as the master, then you just need to make sure you use a different pin for the slave select (SS) on each SPI device.
Is the LPC1768 a SPI or SSP controller?
The NXP LPC1768 contains one SPI (Serial Peripheral Interface) controller and two Synchronous Serial Port (SSP) controllers. The SSP is a Synchronous Serial Port (SSP) controller capable of operation on a SPI, 4-wire SSI, or Microwire bus. In the LPC1768 the SPI is included as a legacy peripheral that can be used instead of SSP0.
How to connect multiple SPI devices using single SELECT line?
Slave-select the expander itself using that single SPI slave-slect line that’s available from the microcontroller. Do a separate SPI transaction to set the I/O expander, before talking to the “payload” device. If you have two lines (in addition to MISO, MOSI, SCLK), you can connect them to a 2-to-4 decoder.
Do you need terminations on a 1 MHz SPI line?
At 1 MHz and 50 mm (2 inches) you don’t need terminations. You have ordinary on-board digital signals, and not even very fast ones. You don’t need pullups or pulldowns on SPI lines. When used, SPI lines are always explicitly driven both directions.
What are the alternate function pins in ssp?
In the example pins P0.15, P0.16, P0.17 and P0.18 are used as SPI alternate function pins. In the SSP implementation P0.16 could be an input or output. If the ARM was to be used as a slave device P0.16 would be an input. In the example the ARM is a master so P0.16 is an output.