Specifications

LEON-G100/G200 - System Integration Manual
GSM.G1-HW-09002-C Preliminary Design-In
Page 57 of 75
2.2.1.7 Digital pins
External Reset (RESET_N): input for external reset, a logic low voltage will reset the module
SIM Card Interface (VSIM, SIM_CLK, SIM_IO, SIM_RST): the SIM layout may be critical if the SIM card is
placed far away from LEON-G100/G200 or in close vicinity of RF antenna. In the first case the long
connection may radiate higher harmonic of digital data. In the second case the same harmonics may be
picked up and create self-interference that can reduce the sensitivity of GSM Receiver channels whose carrier
frequency is coincident with harmonic frequencies. In the later case using RF bypass capacitors on the digital
line will mitigate the problem. In addition, since the SIM card typically accesses by the end use, it may be
subjected to ESD discharges: add adequate ESD protection to improve the robustness of the digital pins
within the module. Remember to add such ESD protection along the path between SIM holder toward the
module
Digital Audio (I2S_CLK, I2S_RX, I2S_TX, I2S_WA): the I2S interface requires the same consideration
regarding electro-magnetic interference as the SIM card. Keep the traces short and avoid coupling with RF
line or sensitive analog inputs;
DDC (SCL, SDA): the DDC interface requires the same consideration regarding electro-magnetic
interference as for SIM card. Keep the traces short and avoid coupling with RF line or sensitive analog inputs;
UART (TXD, RXD, CTS, RTS, DSR, RI, DCD, DTR): the serial interface require the same consideration
regarding electro-magnetic interference as for SIM card. Keep the traces short and avoid coupling with RF
line or sensitive analog inputs.