SIM900D Hardware Design
Debug port:
z
2-wire null modem interface DBG_TXD and DBG_RXD.
z
Can be used for debugging and upgrading firmware.
Phonebook management
Support phonebook types: SM, FD, LD, RC, ON, MC.
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real time clock
Implemented
Timer function
Programmable via AT command
Physical characteristics
Size: 33x 33 x 3 mm
Weight: 6.2g
Firmware upgrade
Firmware upgrade by debug port.
Note: The SIM900D does work, but deviations from the GSM specification may occur.
Table4: Coding schemes and maximum net data rates over air interface
Coding scheme
1 Timeslot
2 Timeslot
4 Timeslot
CS-1:
9.05kbps
18.1kbps
36.2kbps
CS-2:
13.4kbps
26.8kbps
53.6kbps
CS-3:
15.6kbps
31.2kbps
62.4kbps
CS-4:
21.4kbps
42.8kbps
85.6kbps
2.2 SIM900D Functional Diagram
The following figure shows a functional diagram of the SIM900D and illustrates the mainly functional part:
z
The GSM baseband engine
z
Flash and SRAM
z
The GSM radio frequency part
z
The antenna interface
z
The Other interfaces
SIM900D_HD_V1.02
09.04.2010
15
