2.1 General Description
The Designer Systems pHAT-GSM is a quad-band GSM/GPRS module that works on
frequencies GSM850MHz, EGSM900MHz, DCS1800MHz and PCS1900MHz supporting GPRS
class 12 data and Small-Message-System (SMS) functionality. Specifically designed for the
Raspberry-Pi Zero user (can also be used on all the other Raspberry-Pi variants) the pHATGSM
features I2C communication to leave the Raspberry-Pi UART for other functions eg.
sensors etc.
pHAT-GSM features full AT command control over the embedded I2C to UART bridge allowing
the Raspberry-Pi to create GPRS sessions with uplink and downlink transfers at up to 85.6kbps
to support standard Internet service protocols.
The compact form factor, low power consumption and extended temperature range make
pHAT-GSM a best choice for M2M and M2H applications when using the Raspberry-Pi
modules.
The module fully complies with the RoHS/RED directive of the European Union

2.2 Key Features
The following table describes the key features of the pHAT-GSM.
Table 1: Key Features
Features Details
Power Supply  Supply Voltage: 4.5 ~ 5.5VDC
 Typical Supply Voltage: 5.0VDC
Power Consumption  10mA @ 12VDC Idle
 50mA @ 12VDC Peak
Frequency Bands 850/900/1800/1900MHz
Output Power
 Class 4 (2W @ 850/900MHz)
 Class 1 (1W @ 1800/1900MHz)
Sensitivity
 GSM850: -109dBm typ.
 ESM950: -109dBm typ.
 DCS1800: -109dBm typ.
 PCS1900: -109dBm typ.
Data Support  GPRS Class 12: 85.6kbps upload and download
 Integrated TCP/IP protocol
USSD Support Supported
SIM Card Micro SIM(3.0/1.8V)
Indication Blue STATUS LED
Controls Power ON/OFF button (also GPIO controllable)
I2C Speed 400kHz max.
Environmental  Operating Temperature -20℃ to 85℃
 Storage Temperature -30℃ to 125℃
Dimensions 65 x 30 x 4mm
Weight 9.8g approx.
3 Application
3.1 Installation
The module should be attached to the Raspberry-Pi board using a 20+20 2.54mmP pin
header/socket (not supplied).
3.1.1 SIM Card and Antenna
Insert a standard 2G capable micro SIM card into the card connector identified as ‘SIM CARD’
and attach the supplied PCB antenna to the U.FL connector identified as ‘ANTENNA’, ensuring
that the antenna is located away from any metal objects.
3.2 Operation
When power is applied to the pHAT-GSM, from the connected Raspberry-Pi board, it is
possible to either manually power-up the module, by depressing the button identified as
‘POWER’ for > 1 second, or by setting the GPIO23 (pin 16) high for > 1 second. The module will
power-up, indicated by the STATUS indicator flashing, and will register on to the network
provider defined by the inserted SIM card.
Once registered the pHAT-GSM will await incoming AT commands allowing configuration,
SMS send/receive and GPRS data communication.
3.3 Indication
The STATUS indicator is used to provide visual feedback of the current GSM condition. There
are four (4) conditions as follows