4 ms·
that's a good guess. I would agree. SPI is not connection-oriented and "comes up and goes down" (to the extent that it goes up and comes down at all) very fas
by chillingeffect 10y ago
that's a good guess. I would agree. SPI is not connection-oriented and "comes up and goes down" (to the extent that it goes up and comes down at all) very fast with very little active memory needed to support the communication.
- userbinator 10y agoNeither is PS/2, which also being a synchronous serial interface with very low overhead, does share many characteristics with SPI at the physical layer: https://en.wikipedia.org/wiki/PS/2_port#Legacy_port_status_and_USB https://en.wikipedia.org/wiki/PS/2_port#Legacy_port_status_a... The PS/2 interface saves power due to its interrupt-driven nature compared to USB which requires periodic polling, so it is a popular interface for laptops' internal keyboards and pointing devices The major difference is that PS/2 is a de-facto standard up to the application layer/software interface, while the MacBook SPI protocol is unique to Apple.
- mjg59 10y agoPS/2 isn't high enough bandwidth to support decent multitouch, which is why most modern PC touchpads come up in PS/2 mode and then transition to SPI.