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[로봇사이언스몰][Pololu][포로루] Motor Driver and Power Distribution Board for Romi Chassis #3543
Use this motor driver and power distribution board to get your Romi chassis running quickly. It offers all of the same features as the smaller Power Distribution board for Romi Chassis — battery contact slots, reverse voltage protection, several power switching options, and easy access to the various power busses — and adds a two-channel motor driver and powerful switching step-down regulator that can supply a continuous 2.5 A at 5 V or 3.3 V. Just add a microcontroller and sensors to complete your Romi robot.
This motor driver and power distribution board is designed specifically for the Romi chassis as a convenient way to drive the chassis’s motors and power the rest of the electronics that make up your robot. It features two DRV8838 motor drivers, one for each of the chassis’s motors, and a powerful switching step-down regulator that can supply a continuous 2.5 A at 5 V or 3.3 V. The board has slots for soldering in the Romi chassis battery contact tabs, and it incorporates the power switching and distribution functionality from the Power Distribution Board for Romi Chassis, so it offers all of the same features: reverse voltage protection, several power switching options based on the patented latching circuit from the Pololu pushbutton power switch, and easy access to the various power buses.
The board has a small pushbutton already installed for controlling power (one push turns power on and another push turns it off) and offers convenient points for connecting external pushbutton or tactile switches in parallel. It also offers several alternate pushbutton connection options that result in push-on-only or push-off-only operation, and additional inputs enable further power control options like allowing your robot to turn off its own power. Alternatively, the board can be reconfigured to disable the pushbutton circuit and give control to the small installed slide switch.
The board’s control pins and power buses are accessible through a set of 0.1″-spaced pins that are compatible with standard 0.1″ male and 0.1″ female headers, and the power buses are also accessible through a larger set of holes that are compatible with 3.5mm-pitch terminal blocks (you can combine a 2-pin block and a 3-pin block into a single 5-pin block that spans the three power holes and two ground holes).
Two 1/4″ #2-56 screws and two #2-56 nuts are included for mounting the board to the Romi chassis, and two low-profile female headers are included for connecting the motors to the board.
Before installing the motor driver and power distribution board on a Romi chassis, you should solder any headers, terminal blocks, wires, or other connectors you plan to use on the board. You have a few options for connecting the Romi chassis’s motors to the board:
The Romi Encoder can plug directly into the Motor Driver and Power Distribution Board for Romi Chassis.
Please read the rest of this page carefully to determine what additional connectors you might want and where they should be installed.
It is possible to remove the board from the chassis later to solder additional connections, and some of the through holes can be soldered through the slots in the chassis while the board is mounted, but soldering beforehand is easier and avoids the risk of inadvertently melting the chassis with your soldering iron.
The four battery terminals should be soldered to the board after it is mounted on the chassis, as described in the chassis assembly instructions. You will be able to remove the board and battery contacts from the chassis as a single piece after soldering.
Once your you have soldered your through-hole connections to the motor driver and power distribution board, please follow the instructions given in the Pololu Romi Chassis User’s Guide to finish assembling the chassis, mounting the control board, and soldering in the battery contacts. (The diagrams in those instructions show assembly with the larger Romi 32U4 Control Board, but the same steps apply for the smaller motor driver and power distribution board.)
The motor driver and power distribution board has two Texas Instruments DRV8838 motor drivers that can power the Romi chassis’s motors. We recommend careful reading of the DRV8838 datasheet (1MB pdf) for information about the drivers.
By default, the drivers’ motor voltage (VM) is supplied by the board’s switched battery voltage, VSW, and their logic voltage (VCCMD) is supplied by the on-board regulator output, VREG (5 V by default). If you want to customize these voltages, you can cut the jumpers labeled VM = VSW and VCCMD = VREG and connect appropriate supplies to the VM and VCCMD pins.
The DRV8838 offers a simple two-pin PHASE/ENABLE control interface, which this board makes available for each motor as DIR and PWM, respectively. The DIR pin determines the motor direction (low drives the motor forward, high drives it in reverse) and the PWM pin can be supplied with a PWM signal to control the motor speed. The DIR and PWM control inputs are pulled low through weak internal pull-down resistors (approximately 100 kΩ). When the PWM pin is low, the motor outputs are both shorted to ground, which results in dynamic braking of a connected motor.
The two drivers’ SLEEP pins (labeled SLP) are connected together by default and can be driven low to put the drivers into a low-power sleep mode and turn off the motor outputs, which is useful if you want to let the motors coast. The SLEEP pins are pulled high through 10 kΩ pull-up resistors on the board so that the drivers are awake by default. In most applications, these pins can be left disconnected; if you want independent control of SLEEP on each side, you can cut the jumper labeled SLP L = R. The two SLEEP pins should not be driven separately without cutting this jumper.
The following simplified truth table shows how each driver operates:
DIR | PWM | SLEEP | Motor + | Motor − | operating mode |
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0 | PWM | 1 | PWM | L | forward/brake at speed PWM % |
1 | PWM | 1 | L | PWM | reverse/brake at speed PWM % |
X | 0 | 1 | L | L | brake low (outputs shorted to ground) |
X | X | 0 | Z | Z | coast (outputs floating/disconnected) |
The motor driver and power distribution board is designed to allow the Romi Encoder Pair Kit to plug directly into the encoder headers. The encoders can be used to track the rotational speed and direction of the robot’s drive wheels. They provide a resolution of 12 counts per revolution of the motor shaft when counting both edges of both channels, which corresponds to approximately 1440 counts per revolution of the Romi’s wheels. For more information about the specifications of the Romi encoders, please see the Romi Encoder Pair Kit product page.
For typical use, one set of through holes on each side of the motor power and distribution board will be populated with the female header for the encoder board; we recommend using the outer set on each side for this purpose. The remaining set of through holes can be used to make connections to the encoder signals.
For both encoders, channel B leads channel A when the motor is rotating in the forward direction; that is, B rises before A rises and B falls before A falls. Note that this description designates the A and B signals as labeled on the motor driver and power distribution board itself, which puts A in front on both sides.
By default, both the logic voltage for the encoders (VCCENC) and the pull-up voltage for the open-drain encoder outputs (VPU) are supplied by the on-board regulator output, VREG (5 V by default). If you want to customize these voltages, you can cut the jumpers labeled VCCENC = VREG and VPU = VREG and connect appropriate supplies to the VCCENC and VPU pins.
By default, the on-board pushbutton can be used to toggle power: one push turns on power and another turns it off. Alternatively, a separate pushbutton can be connected to the BTNA and BTNB pins and used instead. Multiple pushbuttons can be wired in parallel for multiple control points, and each of the parallel pushbuttons, including the one on the board itself, will be able to turn the switch on or off. The latching circuit performs some button debouncing, but pushbuttons with excessive bouncing (several ms) might not function well with it.
For proper pushbutton operation, the board’s slide switch should be left in its Off position. (Sliding the switch to the On position will cause the board power to latch on, and the switch must be returned to the Off position before the board can be turned off with the pushbutton.)
Alternatively, to disable the pushbutton, you can cut the button jumper labeled Btn Jmp; this transfers control of the board’s power to the on-board slide switch instead. A separate slide or toggle switch can be connected to the GATE pin and used instead.
More advanced control options are available through the button connection pins and four control inputs:
PIN | Description |
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BTNA | Connect through momentary switch to pin “BTNB” for standard push-on/push-off operation. Connect through momentary switch to ground for on-only operation. |
BTNB | Connect through momentary switch to pin “BTNA” for standard push-on/push-off operation. |
ON | A high pulse (> 1 V) on this pin turns on the switch circuit. This pin only functions when pushbutton operation is enabled (i.e. the button jumper has not been cut). |
OFF | A high pulse (> 1 V) on this pin turns off the switch circuit (e.g. allowing a powered device to shut off its own power). This pin only functions when pushbutton operation is enabled. |
CTRL | With pushbutton operation enabled, this pin directly determines the state of the switch circuit. A high pulse (> 1 V) on this pin turns on the switch; a low pulse (e.g. driving the pin low with a microcontroller output line or pushing a button connected from this pin to ground) turns the switch off. Leave this pin disconnected or floating when not trying to set the switch state. Note that this pin should not be driven high at the same time the “OFF” pin is driven high. |
GATE | With pushbutton operation disabled (button jumper cut), this pin controls the state of the switch circuit: driving it low turns the switch on, while letting it float turns the switch off. Connect through slide or toggle switch to ground for on/off operation. Leave this pin disconnected or floating for proper pushbutton operation. We recommend only ever driving this pin low or leaving it floating; this pin should never be driven high while the slide switch is in the “Off” position. |
The diagram below shows the layout of the power distribution buses and access points on the board.
An MP4423H switching buck converter regulates the switched battery voltage (VSW) to provide a regulated output, VREG. The regulated output is 5 V by default, but it can be changed to 3.3 V by cutting the jumper labeled VREG Select. Under typical conditions, up to 2 A of current is available from the VREG output. (We also make a standalone regulator based on this integrated circuit.)
The motor driver and power distribution board’s default configuration provides battery power, VBAT, from all six of the chassis’s AA cells in series (nominally about 7.2 V with rechargeable batteries or 9 V with alkaline batteries). However, the board’s battery jumper, labeled Bat Jmp, allows you to reconfigure the battery connections to provide two independent supplies: BAT1, with 4 cells in series (nominally 4.8 V rechargeable or 6 V alkaline), and BAT2, with 2 cells in series (nominally 2.4 V rechargeable or 3 V alkaline). Cutting the connection between the BAT1− and BAT2+ pads separates the two sets of batteries, and using solder to bridge the BAT1− and GND pads establishes a common ground between the two new supplies.
Warning: Do not bridge the BAT1− and GND pads without first disconnecting BAT1− from BAT2+. Failing to do so could create a short circuit across the BAT2 batteries.
Note that the onboard regulator might not be able to supply 5 V as reliably if VBAT is reconfigured to come from a 4-cell supply, especially if you are using rechargeable batteries.
A simplified schematic diagram of this board is available for download: Schematic diagram of the Motor Driver and Power Distribution Board for Romi Chassis (272k pdf)
In addition to the motor driver and power distribution board, we have a few other boards designed to mount onto a Romi chassis:
Weight: | 20 g1 |
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Current rating: | 5 A2 |
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Motor driver: | DRV8838 |
Motor channels: | 2 |
Minimum operating voltage: | 2.5 V |
Maximum operating voltage: | 10.8 V |
Continuous output current per channel: | 1.8 A3 |
Maximum PWM frequency: | 250 kHz |
Reverse voltage protection?: | Y |
PCB dev codes: | rom02a |
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Other PCB markings: | 0J10078 |
b. 해외상품 :
1) 해당상품: 아이콘이 부착된 상품
2) 구매금액 700,000원 이상 : 입금확인 후 최소 5일 ~ 최대 2주
3) 구매금액 700,000원 이하 : 입금확인 후 최소 1주 ~ 최대 8주
4) 단, 해외계약업체에 품절되지 않은 상품에 한함
② 구매상품 종류가 많을 경우 예상 준비기간 보다 더 소요 될 수 있습니다.
③ 주문하신 상품은 출고완료 메일 또는 문자 수신 후 익일~최대7일(도서,산간지역)
이내에 수령하실 수 있습니다.
④ 제주(\3,500원)/도서지역(\5,000원)은 배송비가 추가됩니다.
제주,도서, 산간지역은 타 지역보다 배송기간이 길어질 수 있습니다.
⑤ 아이콘이 부착된 상품이라도 국내재고가 있을 수 있습니다.
⑥ 해외 현지 사정으로 인해 공지한 배송기간보다 더 길어 질 수 있습니다.
⑦ 해외상품은 반품/교환/취소가 어려울 수 있으니 신중히 주문하시기 바랍니다.
3. 소비자의 단순변심/착오구매에 의한 청약철회제한안내
① 전자상거래 등에서의 소비자보호에 관한 법률 제17조 제2항 및 동 시행령
제21조에 의한 청약철회 제한 사유에 해당하는 경우 및 기타 객관적으로
이에 준하는 것으로 인정되는 경우에 한합니다.
② 소비자의 단순변심, 착오구매에 의한 교환/반품 시에 발생하는 배송비는
소비자가 부담합니다.
③ 판매자의 실수,제품하자 등의 사유로 인한 배송비는 판매자가 부담합니다.
4. 상품의 교환/반품/보증조건 및 품질보증기준안내
① 상품이 공급된 날(배송완료일)로부터 7일 이내에 교환/반품을 신청 할 수 있습니다.
그러나 아래의 사유에 해당 하는 경우에는 교환/반품 신청이 받아들여지지 않을 수도 있습니다.
a. 소비자의 책임으로 인해 상품이 훼손/멸실 된 경우(확인을 위한 포장훼손제외)
b. 소비자의 사용에 의해 상품의 가치가 현저하게 감소한 경우
c. 시간의 경과로 인해 상품의 재판매가 불가하게 된 경우
d. 판매방식의 특성으로 판매자에게 회복할 수 없는 피해가 발생한 경우 (주문제작 상품, 청약철회상품 등)
② 교환/반품/보증조건 및 품질보증기준은 『소비자기본법』에 따른 소비자분쟁해결기준에 따라 피해를 보상합니다.
5. 소비자피해보상 처리, 재화 등에 대한 불만 및 분쟁처리 안내
판매자 | 본사 | 셀러등급 | |
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상호명 | (주)위키모바일(로봇사이언스몰) | 대표자 | 김경식 |
사업자등록번호 | 215-87-14086 | 통신판매신고번호 | 제2008-서울송파-0867호 |
연락처 | 02-2283-1300 | 사업장 소재지 | 서울특별시 송파구 문정동 643-1 엠스테이트 B동704호 |
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쇼핑몰이용안내 | |
전자계약사이트 | |
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회사명 : (주)위키모바일(로봇사이언스몰)
| 사업자등록번호 : 215-87-14086 [사업자정보확인]
| 주소 : 서울특별시 송파구 법원로 114 엠스테이트 B동704호 통신판매업 신고 : 제2008-서울송파-0867호 | 연락처 : 02-2283-1300 | FAX : 02-2283-1304 | 개인정보보호 책임자 : 김 경식 | 대표자 : 김경식 호스팅사업자 : 가비아 퍼스트몰 | contact : ask@wikimobile.co.kr for more information *로봇사이언스몰의 콘텐츠 저작권은 (주)위키모바일에 있으며 무단·전재·복사 배포를 금합니다. |
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