SQ864
GPRS Terminal
10
Sales: +44 (0) 118 967 9000
Fax: +44 (0) 118 976 9020
www.sequoia.co.uk
Rev 2.1.4 Jan 2011
Wireless Technology
Experience The Freedom
6. Power Consumption
The measurement was taken with 2 Voltages (5 V, 12V).
The terminal was connected via RS232 to a PC in order to send/
receive AT commands. The temperature was maintained in a
temperature chamber. The voice call with Power level 5 in GSM
900 was established with a GSM Tester.
SQ864-GPRS
5V
12V
Terminal switched off
0.01 mA 0.67 mA
On, network connection (Idle mode) 71 mA
29 mA
On, network connection voice call (power level 5) GSM 900
235 mA 98 mA
7. Switching the SQ864-GPRS Terminal ON and OFF
The SQ864-GPRS automatically switches on when power is applied
to the terminal . If the unit is then powered off the are two ways to
switch the modem back on again.
•
Either assert TO_IN high (1s < t < 2s)
•
Activate the RS232 control line DTR, high for > 0.2s
The modem is fully operational after 4 seconds. Logging onto the
GSM network may take longer than this and is outside the control
of the modem and is network and frequency dependant. The
modem can is configured to automatically turn on at power up.
Once the modem is switched off a positive signal connected to
TO_IN (pin 4) will switch on the modem.
In this case DTR must be used to switch the modem on again after
it has been switched off or reset, while power is still applied.
NOTE:
DTR must be cycled from low to high.
NOTE:
The TO_IN signal requires a positive “edge” (a “sharp” signal
transition from low to high) to turn the modem on. This transition
should be a rising signal from 0V (GND) to VCC, or at least a large
fraction of that voltage range. Very slow transitions (significantly
slower than many milliseconds) or very small transitions (e.g. only
a few volts instead of 0V to VCC) will not turn on the module (since
they are not considered to be a “positive edge”).
Although this will not be an issue in almost all typical applications
of the modem, under the following condition special design care
has to be taken:
•
Large capacitors in your power supply which will lead to
slow leading and falling edges
•
Slow analogue signals used to assert TO_IN
Both cases above might prevent the modem from recognizing
the power-up signal this is no failure of the modem itself, the
same would apply to almost any electronic device that provides a
separate “power-on” or “reset” signal.
If you are in doubt, please use the following recommendations:
•
Use Vcc power signal from the AC adapter that is
provided with your unit and is known to work properly
with your modem
•
Make sure that your signal and system design adheres to
the recommendations above
•
Consult our support team that will be more than happy
to assist you.
There are three ways to switch off the modem:
•
Use the AT#SHDN command
•
HR_IN (1s < t < 2s)
•
DTR permanently to GND
A delay of up to 10s can be expected for the unit to power off as
the modem logs off the GSM network.
A full system reset, independent of the status of the software, may
be applied to the modem by applying a 2 to 16V active pulse to pin
2 of the RJ12 power connector (RESET_IN). Signal must be active
for at least 200ms then released.
