User's Manual

Note d‘étude / Technical document :
URD1– OTL 5696.1– 003 / 72361 Edition 02
HILO 3G Application Note
17 January 2011 - Page 10 / 38
In cases of long SIM bus lines over 100mm, using serial resistors to avoid electrical overshoots on SIM bus signals is
recommended. Use 56 Ω for the clock line and 10Ω for the reset and data lines.
1
6
5
4 8
7
3
2
9
10
SIM_RST_CARD
SIM_CLK_CARD
VSIM_CARD
SIM_DATA_CARD
VSIM_CARD
SIM_GPIO
C601
10nF
C602
33pF
C60322pF
R601
R602
56
10
10
R601
NC
NC
2.2k R616
GND
Figure 6: Serial resistors for protection of long SIM bus lines
The schematic here above includes the hardware SIM card presence detector. It can be connected to any GPIO and
managed with an AT command.
The SIM card must not be removed from its holder while it is still powered. First switch the module off properly with
the AT command, then remove the SIM card from its holder.
3.2. Connect Audio
The HiLo3G module features two input audio paths and two output audio paths. The two input paths, one is differential
analog microphone and the other is PCM digital input. The two output paths, one is a differential analog 32Ω speaker and
the other is PCM digital output.
In this following chapter design examples will be given including protections against EMC and ESD and some notes about
the routing rules to follow to avoid TDMA noise sometimes present in this sensitive area of design.
3.2.1 PCM Digital Audio
HiLo3G can be used for connections to an external codec through the integrated PCM interface. The interface supports an 8
kHz short sync mode at 2048 kHz and an 8 kHz long sync mode at 128 kHz. In the short-sync (primary PCM) mode, the
HiLo3G can be a master or a slave. In the long-sync (auxiliary PCM) mode, the HiLo3G is always a master; there is no
slave support.