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USBMOD3 User’s Manual

Ravar Pty Ltd Version 1.0 Page 1 of 14 http://www.ravar.net

USBMOD3 - USB Plug and Play Serial Development Module(Second Generation)

The USBMOD3 shown in Diagram 1, is a second generation, low-cost integrated modulefor transferring serial data over USB. Based on the FTDI FT232BM USB UART IC, theUSBMOD3 is capable of transfer rates of up to 1000k baud (RS232) and 3000k baud(RS422 / RS485).

The USBMOD3 offers a complete plug and play solution making it ideal for rapidprototyping and development.

Diagram 1

MODULE FEATURES

• Single module High-Speed USBUART solution

• Based on the FTDI FT232BMHigh-Speed USB UART IC

• Integrated Type-B USBConnector

• On-board 6MHz Crystal

• External EEPROM on board forUSB enumeration data

• No external passive componentsrequired

• Module powered from USB busin addition to supplying up to450mA user application

• 32-pin Dual In-Line PackageIdeal for prototyping

• Fits into a standard 32-pin600mil IC Socket



FT232BM IC FEATURES

• Single Chip Multi-Function DataTransfer Solution

• RS232 link from 300 baud to1000K baud

• RS422/RS485 Link to 3000Kbaud

• 384 byte receive buffer / 128byte transmit buffer for high datathroughput

• Full hardware assisted or X-On/X-Off handshaking

• Support for Event Characters andLine Break condition

• Auto Transmit Buffer control forRS485

• Compact 32 pin (7mm x 7mm)MQFP package

• Integrated 6Mhz – 48Mhz ClockMultiplier aids emissionscompliance

• Integrated 3.3v Regulator – NoExternal Regulator Required

• UHCI / OHCI / EHCI Compliant

• USB 1.1 and USB 2.0Compatible

• USB VID, PID, Serial Numberand Product Description Stringsin external EEPROM.

VIRTUAL COM PORT (VCP)DRIVERS for

• Windows 98, 98 SE and ME• Windows 2000 / XP• Windows CE **• MAC OS-8 and OS9• MAC OS-X **• Linux 2.40 and greater

[** = In planning or under development]

FTD2XX(USB Direct Drivers + DLL S/W Interface)

• Windows 98, 98 SE and ME• Windows 2000 / XP

ENHANCEMENTS

This section summarises the enhancements of the 2nd generation device compared to itsFT8U232AM predecessor. For further details, consult the device pin-out description andfunctional descriptions.

• Integrated Power-On-Reset (POR)CircuitThe device now incorporates an internalPOR function. The existing RESET# pin

(RSTI on the module) is maintained inorder to allow external logic to reset thedevice where required, however formany applications, this pin can now be



either left N/C or hard wired to VCC(+V on the module). In addition, a newreset output pin (RSTO# or RSTO on themodule) is provided in order to allow thenew POR circuit to provide a stable resetto external MCU and other devices.RSTO# was the TEST pin on theprevious generation of devices.

• Integrated RCCLK CircuitIn the previous devices, an external RCcircuit was required to ensure that theoscillator and clock multiplier PLLfrequency was stable prior to enablingthe clock internal to the device. Thiscircuit is now embedded on-chip – thepin assigned to this function is nowdesignated as the TEST pin and shouldbe tied to GND for normal operation.

• Integrated Level Converter onUART interface and control signalsThe previous devices would drive theUART and control signals at 5v CMOSlogic levels. The new device has aseparate VCC-IO (VIO on the module)pin allowing the device to directlyinterface to 3.3v and other logic familieswithout the need for external levelconverter I.C.'s

• Improved Power Managementcontrol for USB Bus Powered, highcurrent devicesThe previous devices had a USBEN pin,which became active when the devicewas enumerated by USB. To providepower control, this signal had to beexternally gated with SLEEP# andRESET#. This gating is now done on-chip -USBEN has now been replacedwith the new PWREN# signal (/PEN onthe module) which can be used todirectly drive a transistor or P-ChannelMOSFET in applications where powerswitching of external circuitry is

required. A new EEPROM based optionmakes the device pull gently down itsUART interface lines when the power isshut off (PWREN# is High). In thismode, any residual voltage on externalcircuitry is bled to GND when power isremoved thus ensuring that externalcircuitry controlled by PWREN# resetsreliably when power is restored.

• Lower Suspend CurrentIntegration of RCCLK within the deviceand internal design improvements reducethe suspend current of the FT232BM tounder 200uA (excluding the 1.5k pull-upon USBDP) in USB suspend mode. Thisallows greater margin for peripherals tomeet the USB Suspend current limit of500uA.

• Support for USB IsocronousTransfersWhilst USB Bulk transfer is usually thebest choice for data transfer, thescheduling time of the data is notguaranteed. For applications wherescheduling latency takes priority overdata integrity such as transferring audioand low bandwidth video data, the newdevice now offers an option of USBIsocronous transfer via an option bit inthe EEPROM.

• Programmable Receive BufferTimeoutIn the previous device, the receive buffertimeout used to flush remaining datafrom the receive buffer was fixed at16ms timeout. This timeout is nowprogrammable over USB in 1msincrements from 1ms to 255ms thusallowing the device to be betteroptimised for protocols requiring fasterresponse times from short data packets.



• TXDEN Timing fixTXDEN timing has now been fixed toremove the external delay that waspreviously required for RS485applications at high baud rates. TXDENnow works correctly during a transmitsend-break condition.

• Relaxed VCC DecouplingThe 2nd generation devices nowincorporate a level of on-chip VCCdecoupling. Though this does noteliminate the need for externaldecoupling capacitors, it significantlyimproves the ease of PCB designrequirements to meet FCC, CE and otherEMI related specifications.

• Improved PreScaler GranularityThe previous version of the Prescalersupported division by (n+0), (n+0.125),(n+0.25) and (n+0.5) where n is aninteger between 2 and 16,384 (214). Tothis we have added (n+0.375),(n+0.625), (n+0.75) and (n+0.875)which can be used to improve theaccuracy of some baud rates andgenerate new baud rates which werepreviously impossible (especially withhigher baud rates).

• Bit Bang ModeThe 2nd generation device has a newoption referred to as “Bit Bang ” mode.In Bit Bang mode, the eight UARTinterface control lines can be switchedbetween UART interface mode and an 8-bit Parallel IO port. Data packets can be

sent to the device and they will besequentially sent to the interface at a ratecontrolled by the prescaler setting. Aswell as allowing the device to be usedstand-alone as a general purpose IOcontroller for example controlling lights,relays and switches, some other

interesting possibilities exist. Forinstance, it may be possible to connectthe device to an SRAM configurableFPGA as supplied by vendors such asAltera and Xilinx. The FPGA devicewould normally be un-configured (i.e.have no defined function) at power-up.Application software on the PC coulduse Bit Bang Mode to downloadconfiguration data to the FPGA, whichwould define its hardware function, thenafter the FPGA device is configured theFT232BM can switch back into UARTinterface mode to allow the programmedFPGA device to communicate with thePC over USB. This approach allows acustomer to create a “generic ” USBperipheral who ’s hardware function canbe defined under control of theapplication software. The FPGA basedhardware can be easily upgraded ortotally changed simply by changing theFPGA configuration data file.Application notes, software anddevelopment modules for thisapplication area will be available fromFTDI and other 3rd parties.

For further information regarding the FTDI FT232BM USB UART IC please refer to theFT232BM Datasheet. This datasheet can be found on the Ravar website athttp://www.ravar.net

As mentioned above in module features, the USBMOD3 is in a 32-pin Dual In-LinePackage. This allows the module to fit into a standard 32-pin 600mil IC Socket, whichmakes the module ideal for prototyping and development work. Shown in Diagram 2below is the pin out for the USBMOD3.



USBMOD3 PINOUT

DIAGRAM 2

On the following page is the pin out table showing what the various pins are on themodule.

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32PINPIN

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16



USBMOD3 PINOUT TABLE

PIN#

SIGNAL TYPE DESCRIPTION

1 G PWR Device – Ground Supply Pin2 GND PWR Device – Ground Supply Pin3 B+ PWR USB Bus Power4 +V PWR Device - +4.4 volt to +5.25 volt Power Supply Pin5 ECS I/O EEPROM – Chip Select6 ECLK I/O EEPROM – Clock7 EDAT I/O EEPROM – Data I/O8 RSTI IN Can be used by external device to reset chip. If not

required tie to VCC9 EP IN Enumeration Power connect to RSTO for bus powered

operation or 3V3 to instruct PC to connect to device10 RSTO OUT Output of the internal Reset Generator. Stays high

impedance for ~2ms after VCC >3.5v and the internalclock starts up, then clamps it ’s output to the 3.3v outputof the internal regulator. Taking RSTI low will also forceRSTO to go high impedance. RSTO is NOT affected by aUSB Bus Reset.

11 3V3 OUT 3.3 volt Output from the integrated L.D.O. regulator. Thispin should be decoupled to GND using a 33nF ceramiccapacitor in close proximity to the device pin. Its primepurpose is to provide the internal 3.3v supply to the USBtransceiver cell and the RSTO pin. A small amount ofcurrent (



USBMOD3 PINOUT TABLE Continued

PIN#

SIGNAL TYPE DESCRIPTION

17 TXLD O.C. LED Drive – Pulses Low when Transmitting Data viaUSB

18 PCTL IN Bus Powered – Tie Low / Self Powered – Tie High19 /PEN OUT Goes Low after the device is configured via USB, then

high during USB suspend. Can be used to control powerto external logic using a P-Channel Logic LevelMOSFET Switch. Enable the Interface Pull-Down Optionin EEPROM when using the /PEN pin this way.

20 TXEN OUT UART – Enable Transmit Data for RS48521 /RI IN UART – Ring Indicator Control Input22 /DCD IN UART – Data Carrier Detect Control Input23 /DSR IN UART – Data Send Ready Control Input24 /DTR OUT UART – Data Terminal Ready Control Output25 /CTS IN UART – Clear To Send Control Input26 /RTS OUT UART – Request To Send Control Output27 RXD IN UART – Receive Data Input28 TXD OUT UART – Transmit Data Output29 GND PWR Device – Ground Supply Pin30 D- I/O USB Data Signal Minus31 D+ I/O USB Data Signal Plus32 G PWR Device – Ground Supply Pin

The following page shows the schematic for the USBMOD3.



USBMOD3 SCHEMATIC

CO

PYR

IGH

T 20

02R

AVA

R P

ty L

td

ww

w.r

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.net

USB

MO

D3

Sche

mat

ic

VC

CR

447

0C

310

0nF

C2

100n

FC

410

0nF

VC

C

R6

10K

R6

C5

33nF

R3

1K5

R1

27R

R2

27R

VCC

FB

1F

erri

te B

ead

1 2 3 4

CO

N1

USB

C2

27pF

C3

27pF

X1

6MH

zVC

C

TXD

25

RX

D24

/RT

S23

/CTS

22

/DTR

21 20

/DC

D19

/RI

18

VCC3

VCCIO13

VCC26

AVCC30

TXE

N16

/PE

N15

PC

TL14

TXL

D12

GND9

GND17

AGND29

USB

DM

8U

SBD

P7

3V3O

UT

6

XTI

N27

XTO

UT

28

EED

ATA

2

EE

SK1

EE

CS

32

/RST

4

RST

OU

T#5

RX

LD11

SLE

EP#

10

TEST

31

U1

FT23

2BM

13 322916214

192021

22232425262728

720

5 1715 1418

GND

DATA

-DA

TA+

+VC

1

10nF

MODULE PINS

MODULE PINS12

10 11 31 30 3

8

9

VC

C

CS

1

SK

2

DIN

3

DO

UT

4

VC

C8

NC

7

NC

6

GN

D5

U2

93LC

66B

R5

2K2

6

C6

10nF

+



Driver Installation

Your first choice when using the USBMOD3 is whether you want to use the VirtualCOM Port driver or the Direct DLL driver.

For programming simplicity, the best driver is the Virtual COM Port and when installed,the USBMOD3 will appear in the System Properties / Device Manager as an USB SerialPort (COMn) as follows.

The COM Port number will vary depending on the number of existing COM Ports onyour computer and the number of USBMOD3’s connected to your system.

To install the Virtual COM Port drivers, download the driver from our website and unzipthe files to a local directory. Then connect the USBMOD3 and windows willautomatically ask for the driver, select to specify a location and browse to the directorywhere you have unzipped the files. (Use the Non Plug & Play driver for the USBMOD3to avoid a delay identifying)



Once the Virtual COM Port is installed it can be programmed exactly as a regular serialCOM port using the MSComm control from Visual Basic or API calls from C or otherlanguages. Set the COM port to the same number as appears in the Device Manager, thebaud rate, stop bits, parity etc are not used as the device always runs at full speed.

The Direct DLL driver is installed in a similar manner but using the alternative downloadfrom the website.

Programming the Direct DLL driver is by call to the DLL Library functions.Please download the Direct DLL programmers guide from the Ravar website.

Application Notes

The USBMOD3 is a quick and simple way of changing from existing RS232 to USB.The existing RS232 interface adaptor can be replaced with a USBMOD3 in a matter ofminutes by connecting TX, RX and handshake lines.

To existing circuitry

TX / Handshakes

RX / Handshakes

MAX232or similarRS232InterfaceAdaptor

DB 9 Pin Connector

Can replace the MAX232 or similarRS232 Interface adaptor with aUSBMOD3

USBMOD3

Connectionto PC via USB

Connectionto PC via Serial

TX / Handshakes

RX / Handshakes

On the following pages there are schematic drawings showing various sampleapplications for the USBMOD3.

The first application is a USB to RS232 converter, which is capable of achieving amaximum of 115k baud. The RS232 interface chip that we are using is a MAX213 chip.



SAMPLE APPLICATION No. 1

RX

Max Baud = 115k

RI

DTR

CTS

TXD

ATA

RTS

RX

DAT

AD

SR

DC

D

SH

IELD

TXD

TXD

ATA

DT

R#

DT

RR

TS

#R

TS

CT

SC

TS

#D

SR

DS

R#

DC

DD

CD

#R

XD

ATA

RXD

RI

RI#

SLE

EP

#V

CC

VC

C

VC

C

MA

X21

3re

leas

ed b

y M

axim

ICs

7 6 20 21 9 4 27 23 18

2 3 1 28

8 5 26

22

19

25 24 131

7

12 141

51

6

1011

T1I

NT

2IN

T3I

NT

4IN

R1I

NR

2IN

R3I

NR

4IN

R5I

N

T1O

UT

T2O

UT

T3O

UT

T4O

UT

R1O

UT

R2O

UT

R3O

UT

R4O

UT

R5O

UT

SH

DN

#E

N

V+

V-

C1+

C1-

C2+ C2-

GN

DV

CC

C7

0.1u

F

C8

0.1

uFSK

T1D

B9M

5 9 4 8 3 7 2 6 1

10

TX

VC

CV

CC

D1

LED

R1

220R

D2

LED

R2

220

R

TX

LED

#

RX

LED

#

This is the maximum

Baud rate which can

be achieved with this

chip

U2

USB

MO

D3

App

lica

tion

Sche

mat

ic

USB

to R

S232

Ser

ial C

onve

rter

To a

max

imum

of 1

15k

baud

C5

0.1

uF

C6

0.1

uF

The

Out

lined

Box

rep

rese

nts

an e

ntir

e U

SBM

OD

3

CO

PYR

IGH

T 20

02R

AVA

R P

ty L

td

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VCC

R4 470

C3

100n

F

C2

100n

FC

410

0nF

VCC

R6 10K

R6

C5

33nF

R3

1K5

R1 27R

R2 27R

VCC

FB1

Ferr

ite B

ead

1 2 3 4

CO

N1

USB

C2 27pF

C3 27pF

X1

6MH

zVC

C

TXD

25

RXD

24

/RTS

23

/CTS

22

/DTR

21 20

/DC

D19

/RI

18VCC

3VCCIO

13

VCC26

AVCC30TX

EN16

/PEN

15

PCTL

14

TXLD

12

GND 9

GND 17

AGND 29

USB

DM

8U

SBD

P7

3V3O

UT

6

XTIN

27

XTO

UT

28

EED

ATA

2

EESK

1

EEC

S32

/RST

4

RSTO

UT#

5

RXLD

11

SLE

EP#

10

TEST

31

U1

FT2

32B

M

13 322916214

192021

22232425262728

720 5 17

15

1418

GND

DATA

-DATA

++V

C1

10nF

MODULE PINS

MODULE PINS

12

10 11 31

30 3

8

9

VC

C

CS

1S

K2

DIN

3

DO

UT

4

VC

C8

NC

7

NC

6

GN

D5

U2

93LC

66B

R5

2K2

6

C6

10nF

+

TXD

DTR

#

RTS

#

CTS

#

DS

R#

DC

D#

RI#

RX

D

TX

LE

D#

RX

LE

D#



Absolute Maximum Ratings

Storage Temperature …………………………………………….. -65°C to + 150°CAmbient Temperature (Power Applied)………………………... 0°C to + 70°CVCC Supply Voltage ……………………………………………. -0.5v to +6.00vDC Input Voltage - Inputs ………………………………………. -0.5v to VCC + 0.5vDC Input Voltage - High Impedance Bidirectionals ……………. -0.5v to VCC + 0.5vDC Output Current – Outputs …………………………………… 24mADC Output Current – Low Impedance Bidirectionals …………... 24mAPower Dissipation ………………………………………………. 500mW

DC Characteristics (Ambient Temperature = 0°C .. 70°C)

Operating Voltage and Current

Parameter Description Min Typ Max Units Conditions

Vcc1 +V Operating SupplyVoltage

4.4 5.0 5.25 V

Vcc2 VIO OperatingSupply Voltage

3.0 - 5.25 V

Icc1 Operating SupplyCurrent

- 25 - mA Normal Operation

Icc2 Operating SupplyCurrent

- 180 200 uA USB Suspend

UART I/O Pin Characteristics (VIO = 5V)

Parameter Description Min Typ Max Units ConditionsVoh Output Voltage High 4.4 - 4.9 V I source = 2 mAVol Output Voltage Low 0.1 - 0.7 V I sink = 4 mAVin Input Switching

Threshold1.1 1.5 1.8 V * Note 1

VHys Input SwitchingHysteresis

200 mV

UART I/O Pin Characteristics (VIO = 3.3V)

Parameter Description Min Typ Max Units ConditionsVoh Output Voltage High 2.7 - 3.2 V I source = 2 mAVol Output Voltage Low 0.1 - 0.7 V I sink = 4 mA

Vin Input SwitchingThreshold

1.0 1.4 1.8 V * Note 1


200 mV

* Note 1 – Inputs have an internal 200kΩ pull-up resistor to VIO



RSTI, ECS, EDAT I/O Pin Characteristics

Parameter Description Min Typ Max Units ConditionsVoh Output Voltage High 4.4 - 4.9 V I source = 2 mAVol Output Voltage Low 0.1 - 0.7 V I sink = 4 mA

Vin Input SwitchingThreshold 1.1 1.5 1.8 V * Note 2


200 mV

* Note 2 – ECS and EDAT pins have an internal 200kΩ pull-up resistor to +V

RSTO Pin Characteristics

Parameter Description Min Typ Max Units ConditionsVoh Output Voltage High 3.0 - 3.6 V I source = 2 mA

Iol Leakage Current Tri-State

- - 5 uA

USB I/O Pin Characteristics

Parameter Description Min Typ Max Units Conditions

UVoh I/O Pins StaticOutput (High)

4.4 - 4.9 V

Rl = 1.5kÙ to3V3Out (D+) Rl= 15kÙ to GND(D+)

UVol I/O Pin StaticOutput (Low) 0.1 - 0.7 V

Rl = 1.5kÙ to3V3Out (D+) Rl= 15kÙ to GND(D+)

UVse Single Ended RXThreshold 0.8 2.0 V

UCom DifferentialCommon Mode

0.8 2.5 V

UVDif Differential InputSensitivity 0.2 V

UDrvZ Driver OutputImpedance

29 44 Ù (ohm) * Note 3

* Note 3 – Driver Output Impedance includes the external 27Ù series resistors on D+ andD- pins.



Technical Support and Further Information

For any questions relating to the USBMOD3 please contact us by Email, Fax or Phone.

Email: [email protected]: +61 755 914364Ph: +61 755 325688

Ravar Pty Ltd Ravar Pty Ltd5G Jackman Center PO Box 2514Jackman Street, Southport SouthportQueensland 4215 Queensland 4215Australia Australia

Product Use Limitations, Warranty and Quality Statement.

The USBMOD3 should not be used in any situation where it’s failure or failure of the PCor software controlling it could cause human injury or severe damage to equipment.This device is not designed for or intended to be used in any life critical application.

The USBMOD3 is warranted to be free from manufacture defects for a period of 12months from the date purchase.Subjecting the device to conditions beyond the Absolute Maximum Ratings listed abovewill invalidate this warranty.The USBMOD3 is a static sensitive device, anti static procedures should be used in thehandling of this device.

All USBMOD3 units are extensively tested at time of manufacture to be free of defects.

Ravar is committed to providing products of the highest quality. Should you experienceany product quality issues with this product please contact our quality assurance managerat the above address.

Disclaimer.

This product and its documentation are provided as-is and no warranty is made or impliedas to their suitability for any particular purpose.Ravar Pty Ltd will not accept any claim for damages arising from the use of this productor documentation.This document provides information on our products and all efforts are made to ensurethe accuracy of the information contained within. The specifications of the product aresubject to change and continual improvement.

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