Nokia Mobile Phones NSE-5 Series, Service Manual, Page: 29 / 327

PAMS
Technical Documentation
NSE–5
System Module
Page 2 – 15
Issue 1 07/99
Infrared Transceiver Module
An infrared transceiver module is designed as a substitute for hardwired
connections between the phone and a PC. The infrared transceiver
module is a stand alone component. In DCT3 the module is located
inside and at the top of the phone.
The Rx and Tx is connected to the FBUS via a dual bus buffer. The
module and buffer is activated from the MAD2_pr1 with a pull up on IRON.
The Accif in MAD2_pr1 performs pulse encoding and shaping for
transmitted data pulses and detection and decoding for received data
pulses.
The data is transferred over the IR link using serial FBUS data at speeds
9.6, 19.2, 38.4, 57.6 or 115.2 kbits/s, which leads to maximum throughput
of 92.160 kbits/s. The used IR module complies with the IrDA SIR
specification (Infra Red Data Association), which is based on the HP SIR
(Hewlett–Packard‘s Serial Infra Red) consept.
The Following figure gives an example of IR transmission pulses. In IR
transmission a light pulse correspondes to 0–bit and a ”dark pulse”
correspondes to 1–bit.
Figure 6. IR transmission frame – example
UART TX
IR TX
startbit stopbit
1
0 1 0 0 1 1 0
constant pulse
The FBUS cannot be used for external accessory communication, when
the infrared mode is selected. Infrared communication reserves the FBUS
completely.