Peripheral Control Module

Figure 11-27. 4PPM Modulation Example

Original

 

 

 

 

Nibble 3

 

 

 

 

 

1

 

0

 

Byte Order

 

 

 

 

 

 

 

 

 

 

 

 

 

Reordered

 

 

0

 

1

 

 

 

 

Nibbles

 

 

 

 

 

 

 

Nibble 0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Chips

 

 

 

 

1

 

 

 

Timeslots

 

1

 

 

3

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

4PPM

 

 

 

 

 

 

 

 

 

 

 

 

Data

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nibble 2

1 1

00

Nibble 1

2

1

2

3

4

Nibble 1

00

11

Nibble 2

3

1

2

3

4

125ns

Nibble 0

01

10

Nibble 3

4

1

 

2

3

4

 

 

 

 

 

Receive data sample counter frequency = 6X pulse width; each timeslot sampled on third clock.

11.10.2.2HSSP Frame Format

When the 4-Mbps transmission rate is used, the high-speed serial/parallel (HSSP) interface within the ICP is used along with the 4PPM bit encoding. The high-speed frame format shown in Figure 11-28is similar to serial port 1’s SDLC format with several minor modifications: the start/stop flags and CRC are twice as long, and instead of one start flag, a preamble and start flag of differing lengths are used.

Figure 11-28. High-Speed Serial Frame Format for IrDA Transmission (4.0 Mbps)

 

 

4 chips

4 chips

8180 chips

16 chips

 

64 chips

8 chips

max

8 chips

(8 bits)

(8 bits)

(32 bits)

 

 

(2045 bytes)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Preamble

Start Flag

Address

Control

Data

CRC-32

Stop Flag

(optional)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Start Flag

00001100000011000110000001100000

 

 

 

 

 

 

 

 

 

 

00001100000011000000011000000110

Stop Flag

 

Preamble

1000000010101000... repeated 16 times

 

 

 

 

 

 

 

 

 

 

The preamble, start, and stop flags are a mixture of chips that contain either 0, 1, or 2 pulses within the four timeslots. Chips with 0 and 2 pulses are used to construct flags because they represent invalid data bit pairings (one pulse required per chip to represent one of four bit pairs). The preamble contains 16 repeated transmissions of the four chips: 1000 0000 1010 1000; the start flag contains one transmission of eight chips: 0000 1100 0000 1100 0110 0000 0110 0000; and the stop flag contains one transmission of eight chips: 0000 1100 0000 1100 0000 0110 0000 0110. The address, control, data, and CRC-32 use the standard 4PPM chip encoding to represent 2 bits per chip.

11-106

SA-1100 Developer’s Manual

Page 256
Image 256
Intel SA-1100 manual Hssp Frame Format