using a multimeter to test serial connection

This method of slave selection is in lieu of the addressing concept as implemented in the I 2C bus. To activate a slave, the master switches the voltage on that SS line to logic low. Normally, when the system powers up, a logic-high voltage from the master is present at the SS pin of each slave device. Because MOSI and MISO are separate lines, data can be conveyed in both directions simultaneously, to the detriment of neither. This line conveys data from the active slave to the master. The line runs to all slaves, but those that are not active ignore it. This is the line that conveys data as transmitted by the master to whatever slave is active. So individual slave data sheets should be consulted in setting up the system. The clock frequency is chosen by the user, but it cannot be faster than permitted for the slowest slave device. The clock exists in the master and a square-wave clock signal is conveyed to the slave that is active. A serial clock line runs from the master to each slave.Typically, SPI operates with a single master device and a number of slaves, although as few as one slave is possible. Logic-low voltage makes the slave active. The SPI bus connections consist of MOSI, MISO and a separate slave select line from the master to each slave. But the wiring between master and slaves is radically different. Both are organized around master/slave architectures. It resembles the I 2C bus, but there are significant differences. Specifically, consider the Serial Peripheral Interface (SPI) bus. The key to understanding and interpreting the serial data and clock streams lies in understanding the inner workings of each individual type of data bus. The Tektronix Series 3000 oscilloscopes can display serial bus activity including data and clock signals on the same time axis. These difficulties can be resolved by using the multi-channel capabilities of advanced oscilloscopes such as the Tektronix Series 3000 instruments. But there are challenges in representing and making sense of the serial data flow in the context of clock timing. A serial bus can be more efficient than the traditional parallel bus.

Using a multimeter to test serial connection