Siemens MC55 User Manual download pdf (Page 17)

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2 - 109 dBm 10 - 93 dBm 18 - 77 dBm 26 - 61 dBm

3 - 107 dBm 11 - 91 dBm 19 - 75 dBm 27 - 59 dBm

4 - 105 dBm 21 - 89 dBm 20 - 73 dBm 28 - 57 dBm

5 - 103 dBm 13 - 87 dBm 21 - 71 dBm 29 - 55 dBm

6 - 101 dBm 14 - 85 dBm 22 - 69 dBm 30 - 53 dBm

7 - 99 dBm 15 - 83 dBm 23 - 67 dBm 31 => - 51 dBm

SIM-card reader

Standard 3V and dual voltage SIM-cards can be used with the GPRS6055. Older 5V SIM cards

will not work, though they may operate in standard GSM cellular phones. The SIM-card holder

has a card detection circuit that will in theory allow hot insertion and removal of the card. This is

NOT recommended, since the SIM card contents can become corrupted if it is removed while the

MC55/56 GSM modem is writing to it.

LED D1 will turn on when a SIM card is enabled.

A very useful AT command that shows detection of the SIM card is: AT^SCID. The SIM card

identifier is given as a reply ^SCID: value shows the ID of the SIM card. If no ID is detected the

MC55/56 can not read the SIM card and can not connect to the GSM service provider network.

To add an entry to your SIM card you may use the AT+CPBW command. In this example we add

the RTD phone number +1-814-234-8087 to the SIM card memory location “1” with the following

AT command set:

AT+CPBW=1, 18142348087, 145, RTD

AT+CREG? Will indicate if the GPRS6055 is logged into the network. If the reply for example is

+CREG: 0, 1 it means that connection to the home network is valid. A complete AT-instruction set

documentation is included in the MC55/56 user’s manual.

GPRS6055ER Digital I/O

The GPRS6055ER has 16 bit-programmable digital I/O bits. RTD’s driver software exports

functions to use the digital I/O and the operation is covered in the Drivers Users Manual. JP4

controls a 10K Ohm pull up/down on DIO bits 1-8 and JP5 controls a 10K Ohm pull up/down on

DIO bits 9 -16. For programming information see GPRS6055 Module Programming section.

Interrupts

Interrupts are used to notify the host CPU that an event happened on a particular device. In

general, interrupts are more efficient than a polling technique, where the CPU must query the

device status at regular intervals. Devices that use interrupts have a special connection to the

CPU, called an interrupt request line (IRQ). When the device needs the CPUs attention, it

asserts the IRQ line. Once the interrupt has been processed, the IRQ line is de-asserted.

The GPRS6055ER uses one ISA interrupt for the GSM. However, it will not actually generate

interrupts unless the Interrupt Enable register has been properly programmed.

Since the GPRS6055ER has 16C550 UARTs, it supports all of the standard serial port interrupt

events. These events include:

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Siemens MC55 User Manual Page 17