User's Manual

HiLo3G-850 User Manual
04 March 2011 - Page 9 / 36
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-850 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-850 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-850 can be a master or a slave. In the long-sync (auxiliary PCM) mode, the HiLo3G-850 is always a master;
there is no slave support.