Intel CONTROLLERS 413808 - Manual (Page 460)

Intel
®
413808 and 413812—SGPIO Unit
Intel ® 413808 and 413812 I/O Controllers in TPER Mode
Developer’s Manual October 2007
460 Order Number: 317805-001US
6.2 Theory of Operation
The SGPIO is used to serialize general purpose I/O signals. For example, the initiator
may want to drive multiple LEDs on the target, and thus do so by sampling and
serializing the parallel initiator LED signals at a fixed sampling rate dictated by the
low-to-high transition of the SLoad signal. Note that SClock is a free-running clock. The
receiver (initiator or target) would then take the bit samples from the bit stream and
converts them into parallel LED signals.
Figure 44 shows the input and output bit streams relative to SClock and SLoad signals.
Note that the SGPIO interface sends a repeating bit stream on SDataOut and receives a
repeating bit stream SDataIn. The bit stream is restarted each time the SLoad signal is
set high. Note that the example in Figure 44 shows four drives and five drives. The bit
stream need not be the same length every time.
6.2.1 SGPIO SClock Output Signal
SClock is a free-running clock, running at a fixed frequency of up to 100 KHz. The rising
edge of SClock is used to transmit SLoad, SDataOut, and SDataIn. The falling edge of
SClock is used to latch SLoad, SDataOut, and SDataIn.
6.2.2 SGPIO SLoad Output Signal
The initiator shall repeatedly send SDataOut bits and receives SDataIn bits. The SLoad
signal indicates when the bit stream is ending or being restarted. After SLoad is
asserted (set to 1), the next four bits positions on SLoad contain a vendor-specific
pattern. Following the vendor-specific pattern, the initiator shall set the SLoad to 0 until
it wants to restart the bits stream.
Figure 44. SGPIO Repeating Bit Stream
SClock
SLoad
SDataOut
SDataIn
D
ri
ve
0
D
ri
ve
1
D
ri
ve
2
D
ri
ve
3
Bit Stream Bit Stream
D
ri
ve
0
D
ri
ve
1
D
ri
ve
2
D
ri
ve
3
D
ri
ve
4
B6343-01
Figure 45. SLoad Signal
0 s
Bit 0
Vendor-Specific
Bit 1
Vendor-Specific
Bit 2
Vendor-Specific
Bit 3
Vendor-Specific
1 Vendor-Specific
… .
1
B6344-01