Visible to Intel only — GUID: hlg1679358639111
Ixiasoft
Visible to Intel only — GUID: hlg1679358639111
Ixiasoft
5.10.6.7.1. Glue Logic for Master Port ss_in_n
When configured as a master, the SPI has an input, ss_in_n. The polarity of this signal depends on the serial protocol in use, and the protocol is dynamically selectable.
Glue logic is required if both of the following conditions are met:
- The serial protocol must be changed dynamically
- One of the protocols being used is SSP
Glue logic is not required under either of the following conditions:
- If dynamically changing the protocol that the SPI master is operating under is not necessary
- If the serial protocol is changed dynamically, but the SSP protocol is not used.
The table below lists the three protocols and the effect of ss_in_n on the ability of the master to transfer data. Note that for the SSP protocol the effect of ss_in_n is inverted with respect to the other protocols.
Protocol |
ss_in_n value |
Effect on Serial Transfer |
---|---|---|
Motorola SPI |
1 |
Enabled |
0 |
Disabled |
|
National Semiconductor Microwire |
1 |
Enabled |
0 |
Disabled |
|
Texas Instruments Synchronous Serial Protocol (SSP) |
1 |
Disabled |
0 |
Enabled |