MB8450 Car Detection Sensor

MB8450 Car Detection Sensor is an ultrasonic sensor with a digital signal output (true / false) that is designed to detect the distance of the car on the drive thru area. This sensor is able to detect the distance of objects in the range of 50 cm to 500 cm and the results of the distance reading will be sent directly to the computer bersistem operating Windows, Mac, and Linux serial via USB cable. The MB8450 also features a simultaneous multi-sensor feature that allows users to integrate multiple sensors within the same system without worrying about interference between signals. The MB8450 is ideal when applied to drive thru ATMs, fast-food restaurants, parking areas, garages, toll gates, and so on.

Specification

- Frequency: 42 KHz

- Output Signal: Digital (true / false)

- Reading Distance: 50 cm - 500 cm

- Interface: USB

- Standardization: IP67

- Supported Operating Systems: Windows, Mac OS, and Linux

- Features: Supports multi-sensor simultaneous feature, equipped with micro USB type B cable for communication to computer

Datasheet

MB1013 HRLV-MaxSonar-EZ1

Ultrasonic sensor module of MaxBotix capable of measuring the distance of an object up to 5m.

• Flow 3,1mA (@ 5VDC)
• The power supply 2,5VDC - 5,5VDC
• Features It has a resolution of 1mm, has kompensi epngukuran results to the ambient temperature.
• Working frequency 42KHz
• Pulse width interfaces, analog Voltage, Serial RS-232 / TTL (jumper settings)
• Distance measuring 1mm - 5m (object detection), 30cm - 5m (distance measurement)

MB7383 HRXL-MaxSonar®-WRLST™

The weather resistant HRXL-MaxSonar-WR is a rugged, ultrasonic sensor component module. This outdoor sensor provides very short- to long- distance detection and ranging in a compact, robust PVC housing. The ultrasonic sensor meets the IP67 water intrusion standard and matches standard electrical 3/4‑inch PVC pipe fittings.

The HRXL-MaxSonar-WRLST MB7383 ultrasonic sensor features a maximum range of 10 meters to large targets. The MB7383 is our most sensitive long-range sensor.

High-output, acoustic power, combined with continuously variable gain, real‑time background automatic calibration, real‑time waveform signature analysis, and noise rejection algorithms results in virtually noise free distance readings. This holds true even in the presence of many of the various acoustic or electrical noise sources. The HRXL‑MaxSonar-WR sensors are factory calibrated to match narrow sensor beam patterns and provide reliable long-range detection zones.

Specifications

• Resolution of 1-mm
• 6Hz read rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 50cm typically range as 50cm
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Real-time automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long, narrow detection zone
• TTL Serial Output
• Great for long-range people detection
• Maximum range of 10 meters (394 inches)

TCT40-16T1 and TCT40-16R1 Ultrasonic Transducer

Ultrasonic Transducer TCT40-16T1 and TCT40-16R1. Both ultrasonic transducer has the same working frequency of 40 KHz, the same capacitance of 2000 (± 30% pF). Different from the second ultrasonic transducer is owned sensitivity.

specifications:
- Capacitance: 2000 (± 30% pF)
- Frequency: 40 KHz
- Sensitivity: -70 dB (TCT40-16R1) and 120 dB (TCT40-16T1)

MB7369 HRXL-MaxSonar-WRM

High Performance Ultrasonic Precision Rangefinder

The HRXL-MaxSonar-WRM ignores smaller targets and only reports the range to target with the largest acoustic return. This is our most advanced weather resistant sensor designed for target detection and ranging outdoors or in tank or bin applications.

The HRXL-MaxSonar-WRM sensors are equipped with filtering firmware which allows the sensor to ignore smaller targets and noise, and still report the target that gives the largest acoustic return. (The sensor will also reject periodic noise, even noise that has a higher amplitude than the acoustic return from the target.) This gives users the flexibility to consistently range larger targets in the presence of clutter and noise. If the largest target is removed from the field of view, the HRXL-MaxSonar-WRM will switch to the target that gives the next largest detectable return.

The Most-Likely filter is designed to report the distance to the largest acoustic return while ignoring smaller targets. When targets are of similar amplitude reflections, preference is given to the closest target.

The MB7360 is the standard RS232 version of this sensor line.

Product Specifications

• Resolution of 1-mm
• 6.66Hz read rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 30cm typically range as 30cm
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Realtime automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long narrow detection zone
• Our most advanced weather resistant, ultrasonic sensor
• Additional stability filter rejects anomalous readings
• Detects the largest signal return in the field of view
• Uses the complete dynamic range of the sensor, if no large targets are present the sensor will select the next smallest target in view
• Can be used to range large objects behind small obstructions
• Best sensor for bin and tank level measurements
• Maximum range of 500 cm (196 inches)
• RS232 serial data output

MB7389 HRXL-MaxSonar-WRMT

The HRXL-MaxSonar-WRMT ignores smaller targets and only reports the range to target with the largest acoustic return. This is our most advanced weather resistant sensor designed for target detection and ranging outdoors or in tank or bin applications.

The HRXL-MaxSonar-WRMT sensors are equipped with filtering firmware which allows the sensor to ignore smaller targets and noise, and still report the target that gives the largest acoustic return. (The sensor will also reject periodic noise, even noise that has a higher amplitude than the acoustic return from the target.) This gives users the flexibility to consistently range larger targets in the presence of clutter and noise. If the largest target is removed from the field of view, the HRXL-MaxSonar-WRMT will switch to the target that gives the next largest detectable return.

The Most-Likely filter is designed to report the distance to the largest acoustic return while ignoring smaller targets. When targets are of similar amplitude reflections, preference is given to the closest target.

Product Specifications

• Resolution of 1-mm
• 6.66Hz read rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 30cm typically range as 30cm
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Realtime automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long narrow detection zone
• Our most advanced weather resistant, ultrasonic sensor
• Additional stability filter rejects anomalous readings
• Detects the largest signal return in the field of view
• Uses the complete dynamic range of the sensor, if no large targets are present the sensor will select the next smallest target in view
• Can be used to range large objects behind small obstructions
• Best sensor for bin and tank level measurements
• Maximum range of 500 cm (196 inches)

URM06-UART Ultrasonic sensor

Ultrasonic sensors emit ultrasonic pulses, and by measuring the time of ultrasonic pulse reaches the object and back to the transducer, the distance of sensor from the target object is calculated. They are widely used in detecting displacement, thickness, distance, water level, material level and transparent objects.

The URM06 - UART Ultrasonic sensor provides very short to long-range detection and ranging from 20cm ~ 10m, comes in a compact, robust PVC housing and matches 35mm electrical pipe mounting. It comes with UART interface and works at high output acoustic power. The ultrasonic sensor detects objects from 20cm to 1000cm and provides range information with 1cm resolution. The URM06 has 15 degree beam angle which has excellent receive sensitivity. And it works best when detecting soft targets. The similar sensors are widely used in professional mobile robot systems such as Pioneer robots.

The URM06 series sensors are the best ultrasonic sensor available in the market regarding its beam angle, senstivity and accuracy.

Specs:

• Working Voltage: 6V-12V (5V is acceptable but not recommended)
• RPeek Current: 2A
• Interface: UART
• Working Frequency: 49.5KHZ
• Working Temperature: -10℃ ~ ＋70℃
• Detecting Angle: 15°（-6dB）
• Detecting Range: 20cm ~ 10m
• Size: 50mm(diameter)*43mm(length)
• Mounting Thread Diameter: 35mm
• Weight: 50g
• ated Current: 16mA

Applications

• robot navigation
• obstacle avoidance
• measuring distance devices
• engineering measurement tools
• industrial control system

MB7387 HRXL-MaxSonar-WRCT

HRXL-MaxSonar - WRCT, Maxbotix MB7387

The MB7387 HRXL-MaxSonar-WRCT offers outdoor ultrasonic rangefinders in an extra-compact housing.

For users that can afford the extra mounting size and weight selecting the similar HRXL-MaxSonar-WR unit is recommended for better performance.

Compact outdoor ultrasonic rangefinder component modules

The HRXL-MaxSonar-WRCT is a weather resistant sensor designed for outdoor detection and ranging.

The weather resistant HRXL-MaxSonar-WRCT is a rugged ultrasonic sensor component module. This outdoor sensor provides very short to long distance detection and ranging in a compact, robust PVC housing. The ultrasonic sensor meets the IP67 water intrusion standard and matches standard electrical 3/4‑inch PCV pipe fittings.

High output acoustic power combined with continuously variable gain, real‑time background automatic calibration, real‑time waveform signature analysis, and noise rejection algorithms results in virtually noise free distance readings. This holds true even in the presence of many of the various acoustic or electrical noise sources. The HRXL‑MaxSonar‑WRC sensors are factory calibrated to match narrow sensor beam patterns and provide reliable long range detection zones.

Component Overview

• Resolution of 1-mm
• 7.5Hz reading rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 30cm range as 30cm
• Maximum Range of 500cm (196 inches)
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Realtime automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long narrow detection zone
• TTL serial output

MB7360 HRXL-MaxSonar-WR

The weather resistant HRXL-MaxSonar-WR is a rugged ultrasonic sensor component module. This outdoor sensor provides very short to long distance detection and ranging in a compact, robust PVC housing. The ultrasonic sensor meets the IP67 water intrusion standard and matches standard electrical 3/4‑inch PVC pipe fittings.

High output acoustic power combined with continuously variable gain, real‑time background automatic calibration, real‑time waveform signature analysis, and noise rejection algorithms results in virtually noise free distance readings. This holds true even in the presence of many of the various acoustic or electrical noise sources. The HRXL‑MaxSonar-WR sensors are factory calibrated to match narrow sensor beam patterns and provide reliable long range detection zones.

Product Specifications

• Resolution of 1-mm
• 7.5Hz read rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 30cm typically range as 30cm
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Realtime automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long narrow detection zone
• RS232 Serial Output

SRF485WPR

The SRF485WPR is a water resistant single transducer ultrasonic ranger. The SRF485WPR uses the RS485 standard for communications, for up to 127 modules on each RS485 bus. The SRF485WPR features an on-board 5v power regulator which can be supplied from 8vdc to 14vdc. Both power and RS485 signals are supplied to the module via a 10pin IDC connector, making cabling a large number of modules very easy. The Range of the SRF485WPR is 60cm to 5meters. 

Specification:

Voltage-12vdc (8vdc - 14vdc)

Current-10mARange-60cm - 5meters

Temperature Compensation--30 to +50 centigrade

Size-40.5mm x 40.5mm (1.6" x 1.6")

Mounting-30.5mm x 30.5mm (1.2" x 1.2")

Transducer-25mm dia. centrally mounted.

MB7076 XL-MaxSonar-WRLA1

MB7076 XL-MaxSonar®-WRLA1™

High Performance Ultrasonic Precision Rangefinder

The XL-MaxSonar-WRLA1 is our longest range (10m) outdoor sensor.

The weather resistant XL-MaxSonar-WR is a rugged ultrasonic sensor component module. This outdoor sensor provides very short to long distance detection and ranging in a compact, robust PVC housing. The ultrasonic sensor meets the IP67 water intrusion standard and matches standard electrical 3/4‑inch PVC pipe fittings.

High output acoustic power combined with continuously variable gain, real‑time background automatic calibration, real‑time waveform signature analysis, and noise rejection algorithms results in virtually noise free distance readings. This holds true even in the presence of many of the various acoustic or electrical noise sources. The XL‑MaxSonar-WR sensors are factory calibrated to match narrow sensor beam patterns and provide reliable long range detection zones.

Product Specifications

• Resolution of 1 cm
• 10Hz read rate
• 42kHz Ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 select sensor outputs: Analog Voltage, Serial, Analog Envelope
• Operates from 3.0-5.5V
• Low 3.4mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational Temperature from -40˚C to +70˚C (-40˚F to +160˚F)
• Real-time automatic calibration (voltage, humidity, ambient noise)
• Firmware filtering for better noise tolerance and clutter rejection
• 200,000+ Hours Mean Time Between Failure
• Weather Resistant (IP67), optional Chemical Resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4" National Pipe Thread Straight)
• Our longest range outdoor, weather resistant, ultrasonic sensor
• Analog envelope output for easy troubleshooting and signal processing
• Maximum range of 1068 cm (450 inches)
• Long range, narrow detection zone

Advanced Ultrasonic Range Finder V1.1

Ultrasonic sensors by JoinMax
specifications:
- 5VDC Power Supply - 8VDC
- Fully compatible with JoinMax RCU
- Distance measurement: 3cm - 300cm
- I2C Interface

Ultrasonic Ranging Module HC - SR04

Ultrasonic Ranging Module HC - SR04

Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm. The modules includes ultrasonic transmitters, receiver and control circuit. The basic principle of work: 

(1) Using IO trigger for at least 10us high level signal,
(2) The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back.
(3) IF the signal back, through high level , time of high output IO duration is the time from sending ultrasonic to returning. Test distance = (high level time×velocity of sound (340M/S) / 2,

Wire connecting direct as following:

• 
  5V Supply 
• 
  Trigger Pulse Input 
• 
  Echo Pulse Output 
• 
  0V Ground 

Electric Parameter 

• Working Voltage DC 5 V 
• Working Current 15mA 
• Working Frequency 40Hz 
• Max Range 4m 
• Min Range 2cm 
• MeasuringAngle 15 degree 
• Trigger Input Signal 10uS TTL pulse 
• Echo Output Signal Input TTL lever signal and the range in proportion 
• Dimension 45*20*15mm 

MS6450 ULTRASONIC DISTANCE METER

MS6450 ULTRASONIC DISTANCE METER

Features:

• Measurement range: 0.6m~ 15m (2’~50’)
• Accuracy: ±(0.5%+1)
• Resolution: 0.01m/1"
• m/feet unit selection
• Area & Volume calculating
• Laser pointer
• Display backlight

MB7366 HRXL-MaxSonar®-WRL™High Performance Ultrasonic Precision Rangefinder

MB7366 HRXL-MaxSonar®-WRL™
High Performance Ultrasonic Precision Rangefinder

The weather resistant HRXL-MaxSonar-WR is a rugged ultrasonic sensor component module. This outdoor sensor provides very short to long distance detection and ranging in a compact, robust PVC housing. The ultrasonic sensor meets the IP67 water intrusion standard and matches standard electrical 3/4‑inch PVC pipe fittings.

The HRXL-MaxSonar-WRL MB7366 ultrasonic sensor features a maximum range of 10 meters to large targets.

High output acoustic power combined with continuously variable gain, real‑time background automatic calibration, real‑time waveform signature analysis, and noise rejection algorithms results in virtually noise free distance readings. This holds true even in the presence of many of the various acoustic or electrical noise sources. The HRXL‑MaxSonar-WRsensors are factory calibrated to match narrow sensor beam patterns and provide reliable long range detection zones.



Component Overview

• Resolution of 1-mm
• 6Hz read rate
• Internal temperature compensation
• 42kHz ultrasonic sensor measures distance to objects
• RoHS Compliant
• Read from all 3 sensor outputs: Analog Voltage, Serial, Pulse Width
• Virtually no sensor dead zone, objects closer than 50cm range as 50cm
• Operates from 2.7-5.5V
• Low 2.9mA average current requirement
• Small, light weight module
• Designed for easy integration into your project or product
• Operational temperature -40°C to +65°C (-40°F to +149°F)
• Realtime automatic calibration (voltage, humidity, and ambient noise)
• Firmware filtering for excellent noise tolerance and clutter rejection
• Weather resistant (IP67), optional chemical resistant F-Option
• Matches standard electrical 3/4-inch PVC pipe fittings for easy mounting (3/4-inch National Pipe Thread Straight)
• Long narrow detection zone
• Our longest range high resolution outdoor, weather resistant, ultrasonic sensor
• RS232 Serial Output
• Maximum range of 10 meters (394 inches)

Ultrasonic Thickness Gage-HP-130D

Ultrasonic Thickness Gage-HP-130D

Basic function

• Measuring Range 1.2～225 mm(steel)
• Accuracy ±(1%H+0.1)mm
• Resolution (<100mm br="" mm="">Sound velocity Range 1000～9999m/s
• Frequency 5MHz
• Operation temperature 0～45℃
• Sensor operation temperatuer 0～60℃
• Two Sensors configuration Ф10 * 2.5Mhz  Ф10 * 5 Mhz
• Minimum limit for Tube measuring Ф10mmprobe：Ф20x3mm(steel)
• LCD backlight
• Low battery indication
• Auto power off
• Weight 290g
• Dimension 136x72x36 mm
• Battery Type 9V(6F22)*1

Ultrasonic thickness meter HP-130

Ultrasonic Thickness Gage-HP-130

Basic function

Measuring Range                             1.2～225 mm(steel)
Accuracy                                         ±(1%H+0.1)mm
Resolution                                        (<100mm br="" mm="">Sound velocity Range                        1000～9999m/s
Frequency                                         5MHz
Operation temperature                        0～45℃
Sensor operation temperatuer              0～60℃
Two Sensors configuration                  Ф10 * 2.5 Mhz
                                                        Ф10 * 5 Mhz
Minimum limit for Tube measuring       Ф10mmprobe：Ф20x3mm(steel)

Data store/recall
Sound Velocity measuring
LCD backlight
Alarm set
Low battery indication
Auto power off
Weight                                                290g
Dimension                                           136x72x36 mm
Battery Type                                        9V(6F22)*1 

Hagisonic AniBat UltraSonic Sensor HG-M40DAI

The Hagisonic AniBat Ultrasonic Sensors use piezo-ceramic elements and are designed for operation in air to help an autonomous mobile robot with obstacle detection and environment recognition. These sensors are compact, light weight, highly sensitive and include a special modulation circuit to reduce click noise. They can be used to initiate and/or detect a pulse. Cable included.

FEATURES:

• Detectable range up to 4m

• Returns a positive TTL level signal proportional to range

• Specialized for robotic applications

• Directional response: 60-70 degrees vertical

• Directional response: 150 degrees horizontal

Hagisonic HG-B40C (5V Type M) Ultrasonic Sensor

Hagisonic HG-B40C (5V Type M) Ultrasonic Sensor

The Hagisonc HG-B40C (5V Type M) Ultrasonic Sensor's are used exclusively for 5V power input. With the power supply, sensors keep transmitting at default transmit condition. This conventional (isotropic) beam type ultrasonic sensor transceiver module with the ASIC Chip on Board. It is supplied with soldering on PCB jumper pad.

• Low voltage (4~5V)
• Supplied with soldering on PCB jumper pad
• Comes with the ASIC Chip on Board

SRF235 Ultrasonic range finder

The SRF235 is a narrow beam ultrasonic ranger, with a beam width of just 15°. An industrial high frequency air coupled transducer operating at 235KHz is used for both Transmit and Receive. The beam patterns below show compare the 15° SRF235 with the 55° typical pattern of the SRF04.

Limitations & Characteristics

235KHz ultrasound does not transmit as easily through air as 40KHz does, so the range of the SRF235 is limited to around 1 meter for normal objects out to a maximum of 1.2 meters for a large surface. The use of a single transducer for both transmit and receive means there is a blanking zone out to 10cm, so the effective range is 10cm to 1.2m. The 235KHz narrow 15° beam behaves more like light on a mirror than 40KHz sensors, so looking at a hard flat surface at an angle of more than 8° or 9° will not yield an echo from that surface. It may be that the reflected beam hits an object and bounces back. In this case the echo from the object will detected and the sonar will indicate the total range of sonar to flat surface + flat surface to object. The flat surface its self will be invisible to the sonar. Under the same circumstances, a 40KHz sensor such as the SRF04 would detect the flat surface - not the reflected object.

The SRF235 detects hard round objects well, such as table and chair legs etc. This makes the SRF235 ideal for detailed local mapping around the robot, but not for longer range sensing. Using the SRF235 along side a 40KHz sonar, makes an excellent sensor combination.

Communication

Communication with the SRF235 ultrasonic rangefinder is via the I2C bus. This is available on popular controllers such as the OOPic, Stamp BS2p, PicAxe etc. as well as a wide variety of micro-controllers. To the programmer the SRF235 behaves in the same way as the ubiquitous 24xx series EEPROM's, except that the I2C address is different. The default shipped address of the SRF235 is 0xE0. It can be changed by the user to any of 16 addresses E0, E2, E4, E6, E8, EA, EC, EE, F0, F2, F4, F6, F8, FA, FC or FE, therefore up to 16 sonar's can be used.

Connections

The connections to the SRF235 are identical to the SRF08and SRF10 rangers. The "No Connection" pin should be left unconnected. It is actually the CPU MCLR line and is used once only in our workshop to program the PIC18F4220 on-board after assembly, and has an internal pull-up resistor. The SCL and SDA lines should each have a pull-up resistor to +5v somewhere on the I2C bus. You only need one pair of resistors, not a pair for every module. They are normally located with the bus master rather than the slaves. The SRF235 is always a slave - never a bus master. If you need them, I recommend 1.8k resistors. Some modules such as the OOPic already have pull-up resistors and you do not need to add any more.