Neoway M590 Installation manual

M590 GPRSModule
HardwareUserGuide
Version 1.2

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd i
Copyright Neoway Technology Co., Ltd 2014. All rights reserved.
Nopart ofthisdocumentmaybe reproduced ortransmittedinanyformor
by anymeanswithoutprior
written consentofShenzhen NeowayTechnology Co.,Ltd.
isthe trademarkofNeowayTechnology Co., Ltd.
All othertrademarksand trade namesmentioned inthisdocumentarethepropertyoftheir respective
holders.
Notice
Thisdocumentisintended for systemengineers (SEs),developmentengineers,and testengineers.
The informationinthisdocumentissubjecttochangewithoutnoticedue toproductversion updateor
otherreasons.
Everyeffort hasbeen made inpreparation ofthisdocumenttoensureaccuracyofthe contents,butall
statements,information, andrecommendationsinthisdocumentdo notconstituteawarrantyofany
kind, express orimplied.
Neowayprovidescustomers completetechnicalsupport.Ifyou haveany
question, pleasecontact
youraccountmanageroremail to the followingemail addresses:
[e-mail]
[e-mail]
Website: http://www.neoway.com.cn

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd ii
Revision Record
Issue Changes RevisedBy Date
V1.0 Initialdraft Qiao Naiwei 2013-10
V1.1 Modified the description ofVCCIO Qiao Naiwei 2014-04
V1.2 Added chapter4. Weng Peibin 2014-05

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd iii
Contents
AboutThis Document.........................................................................................................1
1 Introduction toM590........................................................................................................1
1.1 Overview.....................................................................................................................................1
1.2 BlockDiagram............................................................................................................................1
1.3 Specifications..............................................................................................................................2
2 Pin Description and PCBFootPrint..............................................................................3
2.1 Specificationsand Encapsulation................................................................................................3
2.2 PinDefinition..............................................................................................................................4
2.3 PCB FootPrint............................................................................................................................6
3 Interface Design.................................................................................................................7
3.1 PowerSupplyand Switch Interfaces...........................................................................................7
3.1.1 Design Requirements.........................................................................................................7
3.1.2 VDD_EXT.......................................................................................................................10
3.1.3 Power-On/OffControland Procedure..............................................................................10
3.1.4 RESET .............................................................................................................................13
3.2 UART........................................................................................................................................13
3.3 DTRand RING.........................................................................................................................15
3.3.1 DTRPin...........................................................................................................................15
3.3.2 RING SignalIndicator.....................................................................................................16
3.4 SIMCard Interface....................................................................................................................16
3.5 Running LEDIndicator.............................................................................................................18
3.6 RFInterface...............................................................................................................................19
3.6.1 RFDesign and PCBLayout.............................................................................................19
3.6.2 Recommended RFConnection.........................................................................................21
4ElectricFeatures and Reliability .....................................................................................22
4.1 Electric Feature.........................................................................................................................22
4.2 Temperature...............................................................................................................................22
4.3 Current......................................................................................................................................23
4.4 ESDProtection..........................................................................................................................23
5 RFFeatures.......................................................................................................................25
5.1 WorkBand................................................................................................................................25
5.2 Transmitting PowerandReceiving Sensitivity.........................................................................25
5.2.1 Transmitting Power..........................................................................................................25
5.2.2 Receiving Sensitivity.......................................................................................................26
6 Mountingthe Module ontothe Application Board..................................................27
7 Package..............................................................................................................................27
8 Abbreviations...................................................................................................................28

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd iv
TableofFigures
Figure2-1 TopviewoftheM590 module...............................................................................................3
Figure2-2 PCBfootprintrecommendedfor M590 (unit: mm)..............................................................6
Figure3-1 Currentpeaksandvoltagedrops............................................................................................7
Figure3-2 Capacitorsusedfor thepower supply....................................................................................8
Figure3-3 Reference design ofpower supplycontrol.............................................................................8
Figure 3-4 Reference designofpower supplycontrolledbyp-MOSFET...............................................9
Figure3-5 Reference designsofseparatedpower supply......................................................................10
Figure3-6 Power-onprocedure............................................................................................................. 11
Figure3-7 Power-offprocedure............................................................................................................. 11
Figure3-8 Reference circuit for power-on/offcontrol...........................................................................12
Figure3-9 Reference circuit for power-on/offcontrolledbyhighlevel................................................12
Figure3-10 Reset circuit withtriodeseparating....................................................................................13
Figure3-11 Signal connectionbetweenDCE andDTE.........................................................................13
Figure3-12 Recommendedcircuit for thecommunicationbetween3.3VMCUandUART................14
Figure3-13 Recommendedcircuit for thecommunicationbetween5VMCUandUART...................14
Figure3-14 RING indicator for incomingcall......................................................................................16
Figure3-15 RING indicator for SMS....................................................................................................16
Figure3-16 Reference design ofSIM card interface.............................................................................17
Figure3-17 Reference ofSIM card socket............................................................................................17
Figure3-18 LEDindicator.....................................................................................................................18
Figure3-19 Reference design for antennainterface..............................................................................19
Figure3-20 RFlayoutreference............................................................................................................ 20
Figure3-21 Reference RFdesign whenpin21 isnotused....................................................................20
Figure3-22 EncapsulationspecificationsofMurata RFconnector....................................................... 21

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd v
Table of Tables
Table 1-1 M590specifications.................................................................................................................2
Table 2-1 M590pindefinition.................................................................................................................4
Table 3-1 Power supplyandswitchinterface..........................................................................................7
Table 3-2 UART....................................................................................................................................13
Table 3-3 DTRandRING pins..............................................................................................................15
Table 3-4 SIM Card Interface................................................................................................................16
Table 3-5 LEDindicator........................................................................................................................18
Table 4-1 Electric featureofthemodule................................................................................................22
Table 4-2 TemperatureFeature..............................................................................................................22
Table 4-3 Currentfeature.......................................................................................................................23
Table 4-4 ESD featureofthemodule....................................................................................................23
Table 5-1 Workband..............................................................................................................................25
Table 5-2 Transmittingpower(EGSM900)...........................................................................................25
Table 5-3 Transmittingpower(DCS1800)............................................................................................25

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 1
AboutThis Document
Thisdocumentdefinesthe features, indicators, and teststandardsofthe M590 moduleand provides
reference forthe hardware design ofeach interface.With M590 GPRS ModuleATCommand Set, thisuser
guide can help you completewireless communication application easily.
1Introduction toM590
M590 isacompactwireless GPRSmodulethatsupports downlink EDGE. Itcan provide functionsofSMS
and data servicesand iswidelyused in industrialand consumerfields.
1.1 Overview
NeowayM590 module adopts21-pinLCC encapsulation and itsdimensionsare 27.6 mmx 21.6 mmx 2.6
mm.Itprovidescustomers the following hardware resources:
lUARTinterfaces, used fordata communication, firmware updating and commissioning
l10-bit ADC input, voltage ranging from0 Vto 2.8 V
lAdapting to1.8 Vand 3.0VSIMcard
lSupporting RING/LIGHT/DTR (sleep mode)functions
lSupporting time updating
1.2 BlockDiagram
The M590 module consistsofbasebandcontroller, FlashROM,RFsection, application interfaces, etc. All
sectionscoordinate with each otherto provide such communication functionsasGPRS dataand voice.
The following figure showsthe block diagramofM590.
DTR
RING
UART
ADC
SIM

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 2
1.3 Specifications
Table 1-1 M590specifications
Specifications Description
Band EGSM900/DCS1800 MHzdual-band
Supporting band locking
Sensitivity <-107 dBm
Max. transmit power lEGSM900 Class4(2W)
lDCS1800 Class1(1W)
Protocol Compatible with GSM/GPRSPhase2/2+
AT lGSM07.07
lExtended ATcommands
SMS lTEXT/PDU
lSupporting SMSmessage receiving and transmitting and alert fornew
SMS messages
lSupporting SMS message management: reading/deleting/storage/list
GPRS feature lGPRSCLASS 12
lMax. theoretic uplink rate:85.6 Kbit/s
lMax. theoretic downlink rate:85.6 Kbit/s
lBuilt-in TCP/IPprotocol, supporting multiple links
lSupporting serverand clientmodes
Circuit Switch Data lCSDdata service
lUSSD
UART
lSupporting UARTmultiplexing
lSupporting ATsending, datatransmission, and software download
lSupporting baudrate from1200 bit/sto 115200 bit/s
CPU ARM7-EJ@360MHz
Antenna feature 50 Ωimpedance
Operating temperature -40 to +85
Operating voltage 3.5 Vto 4.3 V(3.9 Visrecommended)
Peak current Max 2.0 A
Idle current 18 mA
Currentin sleep mode <2 mA(live network)
<1 mA(instrument, DRX=9)

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 3
2Pin Description and PCBFootPrint
2.1 Specificationsand Encapsulation
Specifications M590
Dimensions 27.6 mm x 21.6 mmx 2.6 mm(Hx W x D)
Weight 2.6 g
Encapsulation 21-pinLCC
Figure 2-1 Top viewoftheM590 module
SIMGPRS_ANT Other NC
1
2
3
4
5
6
7
8
9
10 11
12
13
14
15
16
17
18
19
20
21
GND
VBAT
VBAT
GND
LIGHT
VDD_EXT
URXD
UTXD
DTR
RING SIM_DATA
SIM_CLK
SIM_RST
VSIM
GND
ADC_IN
NC
RESET
ON/OFF
GND
GPRS_ANT
Power GND UART ADC
M590
TOP View

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 4
2.2 PinDefinition
Table 2-1 M590 pindefinition
Pin Name I/O Function Reset
Status
LevelFeature
(V) Remarks
PowerSupplyand Switch Interfaces
2, 3 VBAT P Mainpowersupply
input
3.5 Vto4.3 V(3.9 V
isrecommended)
6 VDD_EXTP 2.8 Vpowersupply
output
SupplypowerforIO
levelshifting circuit.
Load capability:less
than 50 mA
1, 4,
15, 20 GND P Ground
19 ON/OFF DI On/Off input
0<VIL<0.6
2.1<VIH<VBAT
Lowlevelpulse can
change theOn/Off
state.
18 RESET DI Resetinput
0<VIL<0.6
2.1<VIH<3.1
Internallypulled up
to 2.8V
Lowlevelreset
UARTInterface
7 URXD DI UARTdata receive
I/PU 0<VIL<0.6
2.1<VIH<3.1
0<VOL<0.42
2.38<VOH<2.8
With 47Kpull-up
inside
8 UTXD DO UARTdata
transmit
SIMCard
11 SIM_DATA
DI/O
SIMcard data IO
0<VIL<0.25*VSI
M，
0.75*VSIM<VIH
<VSIM
0<VOL<0.15*VS
IM
0.85*VSIM<VOH
<VSIM
Compatible with
1.8/3.0 VSIMcard
12 SIM_CLK DO SIMcard clock
output
13 SIM_RST DO SIMcard reset
output
14 VSIM P SIMcard power
supplyoutput
LEDIndicators
5 LIGHT DO StatusLED I/PD
2.8 V/4 mAoutput
Sleep Mode Controlling
9 DTR DI Signalfor controlling sleep
mode I/PD
0<VIL<0.6
2.1<VIH<3.1
0<VOL<0.42
Lowlevelbydefault
Used togetherwith
ATcommands

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 5
2.38<VOH<2.8
SMS and Incoming Call Ring
10 RING DO Ring output I/PD
0<VIL<0.6
2.1<VIH<3.1
0<VOL<0.42
2.38<VOH<2.8
Detectincoming
SMS messagesor
calls
ADCDetecting
16 ADC_IN AI 10-bitADC input
Detectable voltage
range:0 Vto 2.8V
GPRSAntenna
21 GPRS_ANT
AI/O
GPRS antenna
interface 50 Ωimpedance
Reserved Pins
17 NC
Mustbe left
disconnected.
P:indicatespowersupplypins
NC:indicatespinsthatare notsupported and mustnotbe connected
DI:indicatesdigitalsignalinputpins
DO:indicatesdigitalsignaloutputpins
I/PD:indicatesdigitalsignalinputpinswith pull-down
I/PU:indicatesdigitalsignalinputpinswith pull-up
AI:indicatesanalogysignalinputpins
AO:indicatesanalogysignaloutputpins
The maximuminputvoltage atall IOports (including peak signalcurrent) cannotexceed 3.1 Vbecause
the module usesa 2.8 VIOpowersystem.In the application ofthe module, the IOoutputvoltage fromthe
3.3 Vpowersupplysystemofthe externalcircuit mightgreatlyovershoot3.1 Vdueto the signalintegrity
design. In thissituation, the IOpinsofthe module mightbe damaged if the IOsignalsare connected to the
IOport on the 2.8-Vsystem.To rectifythisissue, take measuresto match the level.Fordetails, see the
Section 3.2 UART.

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 6
2.3 PCBFootPrint
LCC packaging isadopted topackage the pinsoftheM590 module. Figure 2-2 showsthe recommended
PCBfootprint.
Figure 2-2 PCBfootprintrecommendedforM590 (unit:mm)
21.2
27.6
2.54
21.6
3.4
4.0
2.35
M590
Pads1~20:1.8*2.4
Pad21:1.2*1.6
Pitch：X=21.2；Y=2.54
Unit：mm
Copper Cut
D=2.0

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 7
3InterfaceDesign
3.1 PowerSupplyand SwitchInterfaces
Table 3-1 Powersupplyandswitch interface
Signal I/O Function Remarks
VBAT P Main powersupplyinput 3.5 Vto 4.3 V(3.9 Visrecommended)
VDD_EXT P 2.8 Vpowersupplyoutput Loading capability<50 mA
RESET DI Module resetinput Resetatlowlevel
Min. 50 ms
100 msisrecommended
ON/OFF DI On/Off input Lowlevelpulsecan changethe On/Off state.
3.1.1DesignRequirements
VBAT isthe main powersupplyofthe module. Its inputvoltage rangesfrom3.5 Vto 4.3 Vand the
preferable value is3.9V.Itsuppliespowerforbaseband controllerand RFpoweramplifier.
The performance oftheVBATpowersupplyisa criticalpath to module'sperformance and stability. The
peak inputcurrentatthe VBATpin can be upto 2 Awhen the signalisweak and the module worksatthe
maximumtransmitting power. The voltage will encountera drop in such a situation. The module might
restart if the voltage dropslowerthan 3.5 V.
Figure 3-1 Currentpeaksand voltagedrops
Keepabove3.5V
Keepabove3.5V
3.5V
3.5V
0ms
0ms 3.7ms
3.7ms 7.4ms 7.4ms 10.7ms 10.7ms T
T
2.0A
2.0A
Voltage
Voltage
Input
Current
Input
Current
3.9V
3.9V

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 8
Figure 3-2showsa recommended powersupplydesign forthe module.
Figure 3-2 Capacitorsusedforthe powersupply
Inthe circuit,you can useTVSatD1toenhance the performance ofthe moduleduringaburst.SMF5.0AG
(Vrwm=5V&Pppm=200W)isrecommended.Alarge bypass tantalumcapacitor(220 μFor100μF)or
aluminumcapacitor(470 μFor1000 μF)isexpected atC1 to reduce voltage dropsduring bursts together
withC2(10μFcapacitor).Inaddition, you need toadd0.1 μF,100 pF,and 33 pFfiltercapacitors toenhance
the stabilityofthe powersupply.
Acontrollable powersupplyispreferable if used in harshconditions.The module mightfail to resetin
remoteorunattended applications,orinan environmentwithgreatelectromagneticinterference (EMI).You
can use the ENpin on the LDOorDC/DCchipsetto controlthe switch ofthe powersupplyasshown in
Figure 3-3.
MIC29302WUin thefollowing figure isan LDO and outputs3 Acurrentto ensure the performance ofthe
module.
Figure 3-3 Reference design ofpowersupplycontrol
The alternative wayisto usea p-MOSFETto controlthe module'spower, asshown inFigure 3-4. When
the externalMCUdetectsthe exceptionssuch asno response fromthe module orthe disconnection of
GPRS, poweroff/on can rectifythe module exceptions.In Figure 3-4, the module ispowered on when
GPRS_ENissetto high level.
VCC_IN_5V
GPRS_EN VBAT
100uF
TAN 0.1uF
TVS
5V 10uF
470uF
TAN
10K
4.75K
VOUT
MIC29302WU
EN
VIN ADJ 0.1uF 100pF 33pF

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 9
Figure 3-4 Reference design ofpowersupplycontrolled byp-MOSFET
Q2isaddedtoeliminatethe need forahigh enough voltage levelofthe hostGPIO.Incasethatthe GPIOcan
outputahighvoltage greaterthan VCC_IN_3.9V-|VGS(th)|,whereVGS(th) is the GateThresholdVoltage, Q2
isnotneeded.
Referencecomponents:
lQ1 can be IRML6401 orRds(on)p-MOSFETwhich hashigherwithstand voltage anddrain current.
lQ2:a common NPNtransistor, e.g. MMBT3904;oradigitalNPNtransistor, e.g. DTC123.Ifdigital
transistorisused, delete R1and R2.
lC3:470uFtantalumcapacitorrated at6.3V;or1000 uFaluminumcapacitor.Iflithiumbatteryis
used to supplypower, C3 can be 220 uFtantalumcapacitor.
Protection
Place a TVS diode (VRWM=5V)onthe VBATpowersupplyto ground, especiallyin automobile
applications. Forsome stablepowersupplies, zenerdiodescan decrease the powersupplyovershoot.
MMSZ5231B1T1GfromONSEMIand PZ3D4V2 fromPrisemiare options.
Trace
The trace widthofprimaryloop linesforVBATon PCBmustbe abletosupport the safetransmission of2A
currentand ensure no obviousloop voltage decrease.Therefore, the trace width ofVBATloop line is
required 2 mm and the ground should be ascomplete aspossible.
Separation
Asshown inFigure 3-1, the GPRSmodule worksin burst mode thatgeneratesvoltage dropson power
supply. And furthermore thisresultsin a 217Hz TDDnoise through power(One ofthe waygenerating
noise.Anotherwayisthrough RFradiation).Analog parts,especiallythe audiocircuits,aresubjected tothis
noise, knownasa"buzznoise"inGSMsystems.Topreventotherparts frombeing affected, it'sbettertouse
S
G
D
VCC_IN_3.9V VBAT
10K
100K 33pF
10uF
GPRS_EN
2K
10K
0.1uF
Q1
R4
C1 C2 C4 C5 C7
R1
R2
10uF0.1uF R3
Q2
TVS
5V 470 uF
C3 C6
100pF

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 10
separated powersupplies.The module shall be supplied by an independentpower, likea DC/DCorLDO.
See Figure 3-5.
DC/DCorLDO should outputrated peak currentlargerthan 2 A.
The inductorused inReference Design (b), should be a powerinductorand have a verylowresistance. 10
uHwith average currentabilitygreaterthan 1.2Aand lowDC resistance isrecommended.
Figure 3-5 Reference designsofseparated powersupply
Never use adiode to make the drop voltage between a higherinputandmodule power. Otherwise,
Neowaywillnotprovide warrantyforproductissuescaused bythis.In thissituation, the diode will
obviouslydecrease the module performances, orresult in unexpected restarts, due to the forward voltage
ofdiode will varygreatlyin differenttemperature and current.
EMC Considerations
Place transientovervoltage protection componentslike TVSdiode onpowersupply, to absorb the power
surges. SMAJ5.0A/Ccouldbe a choice.
3.1.2VDD_EXT
Itisrecommended thatVDD_EXTisonlyused forinterface leveltransformation. VDD_EXTcan output
2.8 Vand50 mA. Itstopsoutputafterthe module isshutdown.
3.1.3Power-On/OffControlandProcedure
Priorto turningon the module, poweron the hostMCUand finish the UARTinitialization.Otherwise
conflictionsmayoccurduring initialization, due to unstable conditions.
ON/OFFisa lowlevelpulseactive input, used to turn on oroffthe module.
Power-On Procedure
While the module isoff, drive the ON/OFF pin to ground foratleast 1.2 second and then release, the
modulewillstart.Anunsolicited message (+MODEM:STARTUP)will be senttohostthrough UARTport,
indicating thatthe module ispowered on and can respond toATcommands.
When you design yourprogram,you can use the unsolicited message (MODEM:STARTUP)to check
whetherthe module isstarted orresetimproperly.

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 11
Figure 3-6 Power-on procedure
Power-Off Procedure
While the module ison, drive the ON/OFF pin to ground foratleast500 ms and then release, the module
will trytodetach tonetworkand normally2secondslaterit willshutdown. Anotherapproach toturnoffthe
module isusing ATcommands. Fordetails, see M590 GPRS ModuleATCommands.Figure 3-7 showsthe
power-offprocedure ofthe module.
Figure 3-7 Power-offprocedure
Power-On/Off Control
Figure 3-8 showsa reference circuit forON/OFFcontrolwith inverted controllogic.
VBAT
ON/OFF
VDD_EXT
UART
1.2s
3s
300ms
VBAT
ON/OFF
VDD_EXT
UART
2 s
500ms

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 12
Figure 3-8 Reference circuitforpower-on/offcontrol
Figure 3-9 Reference circuitforpower-on/offcontrolled byhigh level
InFigure 3-9, high leveltakeseffectfor ON/OFF on the userside (USER_ON)afterlevelshifting.
R1 and R2 can be adjustedaccording to the driving capabilityofthe USER_ONpin.
Use a common NPNtransistor, e.g. MMBT3904;oradigitalNPNtransistor, e.g. DTC123.Ifdigital
transistorisused, delete R1and R2.
lLevelabnormalitiesatinterfacesconnected to the externalMCU, especiallythe UARTport, might
affectthe power-on procedure ofthe module. Forexample, when a module isturned on, the IOports
ofthe MCUarestill in outputstatusbecause theyhave notbeen initialized completely.The module
mightfailsto start ifthe UTXDsignal(outputpin)isforced to pull up ordown.
lThe betterwayto rescue the module fromabnormalcondition, isto applya powerOFF-ON procedure,
ratherthan using the ON/OFFcontrolsignal. In factON/OFFsignalissoftware-dependent.
GPRSModule
ON/OFF
TVS
S1
USER_ON GPRSModule
ON/OFF
4.7K
47K
R1
R2

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 13
3.1.4RESET
You canresetthe moduleby keeping the RESETpinlowlevelformorethan 100 ms.The pinispulled upby
an internalresistorandthe typicalhigh levelis2.8V.TheRESETpincan beleft disconnected if notused.If
you use 3.3 VIOsystem,you are advised to separate it by using triode. Pleasereferto Figure 3-10.
Figure 3-10 Resetcircuitwithtriodeseparating
3.2 UART
Table 3-2 UART
Signal I/O FunctionDescription Remarks
URXD DI UARTdata receive
UTXD DO UARTdata transmit
UARTisused forATcommands, data sending/receiving, firmware updating, etc. Figure 3-11showsthe
signalconnection between the module (DCE)andthe terminal(DTE).
Figure 3-11 Signalconnection between DCE and DTE
The UARTofM590worksat 2.8 V CMOSlogiclevel.Thevoltagesforinputhigh levelshould not exceed
3.1 V.Supported baud ratesare1200, 2400,4800, 9600, 14400, 19200,38400, 57600,115200bit/s,and the
default rate is 115200 bit/s.
RESET
VDD_EXT
4.7K
47K GPRSModule
DCE
URXD
UTXD
DTE
UTXD
URXD

M590 GPRSModule HardwareUser Guide
Copyright Neoway TechnologyCo., Ltd 14
Ifthe UARTisinterfacing with a MCUthathas3.3Vlogic levels, it isrecommended thatyou add a level
shifting circuit outside ofthe module.
Figure 3-12 Recommended circuitforthe communication between 3.3VMCU and UART
In Figure3-12, 100 pFfiltercapacitorshouldbe placed nearthe receivepinofthe module. Resistance (200
Ωto 470 Ω)and capacity(100 pFto 470 pF)can be selected based on the tested signalwave. Greatserial
resistance andfiltercapacitywill decrease the signallevel, resulting ingreatsignalwave distortion and the
lowadaptableUARTcommunication baudrate.RB521S-30TE-61, RB521SM-30GJT2R, and
LRB521S-30T1Gare recommended forseparating diode.
When the externalMCU adopts5 VIOsystem, levelshifting isrequired forbothUARTreceive and
transmit.Figure 3-13showsa reference circuit.
Figure 3-13 Recommended circuitforthe communication between 5VMCU and UART
Module_URXD
Module_UTXD
VDD_EXT
0.1uF
47K
RB521S
200
33pF
33 pF
MCU_UTXD
MCU_URXD
INPUT OUTPUT
VCC_IN VCC_OUT
4.7K 10K
Q1
R2 R3