Difference between revisions of "Servo"

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m (moved SPI Servo to Servo: now for both SPI and I2C)
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[[File:SPI_Servo.jpg|thumb|300px|alt=The SPI_Servo PCB|The SPI_Servo PCB]]
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[[File:SPI_Servo.jpg|thumb|300px|alt=The SPI_Servo PCB|The Servo PCB (SPI version photographed)]]
  
This is the documentation page for the SPI_servo board.  
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This is the documentation page for the SPI_servo and I2C_SERVO boards.  
  
 
== Overview ==
 
== Overview ==
  
This module enables you to easily control upto 7 servomotors over an SPI interface, while needing minimal resources from your CPU.
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This module enables you to easily control upto 7 servomotors over an SPI or I2C interface, while needing minimal resources from your CPU.
The PCB is equipped with two SPI connectors, so daisychaining multiple SPI modules is an option.<br>
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The PCB is equipped with two SPI or I2C connectors, so daisychaining multiple SPI or I2C modules is possible.<br>
This allows you to control the LCD with only 4 data lines (MOSI, MISO, SS and SCK). This is not only pin-saving, but is is also possible do daisy-chain multiple modules (we will be releasing additional boards with other functions in the very near future)!<br>
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This allows you to control a chain of boards with only 4 data lines (MOSI, MISO, SS and SCK) for SPI or two lines (SDA, SCL) for I2C. This is not only pin-saving, but is is also possible do daisy-chain multiple modules (we will be releasing even more boards with other functions in the very near future)!<br>
The board can be used with all microcontrollers, such as the Atmel AVR, Arduino/Freeduino boards, Microchip PIC, etcetera. Other computers/boards with an SPI interface (such as the Raspberry Pi) should also be able to control this module.<br>
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The board can be used with all microcontrollers, such as the Atmel AVR, Arduino/Freeduino boards, Microchip PIC, Raspbery PI etcetera. <br>
 
<br>
 
<br>
For small servos, the power supplied by the SPI connector is enough. For larger servos however, the voltage drop may be to high. We suggest conneting an auxillary 5V power source to the PCB, and cutting the trace connecting the servo power rail to the SPI power rail. Future versions will have a jumper for this cause, and a dedicated servo power connector.
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For small servos, the power supplied by the SPI or I2C connector is enough. However current surges of up to a whole ampere are easily achieved even when two or three smaller servos need to move simultaneously. For larger servos however, the voltage drop may be to high. We suggest conneting an auxillary 5V power source to the PCB, and move the jumper.
  
 
== External resources ==
 
== External resources ==
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Solder jumper (on bottom layer): ICSP-Enable. CAUTION! Pin 1 and 2 are connected by a narrow PCB track. Cut this if you want to change this jumper setting.<br>
 
Solder jumper (on bottom layer): ICSP-Enable. CAUTION! Pin 1 and 2 are connected by a narrow PCB track. Cut this if you want to change this jumper setting.<br>
 
1-2: Default: Both SPI connectors connected in parallel.<br>
 
1-2: Default: Both SPI connectors connected in parallel.<br>
2-3: ICSP enabled; programming the MCU over the 6-pin connector marked SPI3 (near the edge of the board) is enabled.<br>
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2-3: ICSP enabled; programming the MCU over the 6-pin connector. This connector may be marked SPI1 or SPI3 (near the edge of the board, furthest from the CPU.)<br>
  
 
== Programming ==  
 
== Programming ==  
  
To control the servos, you need to send things over the SPI bus to the PCB. The [[spi_servo 1.0_protocol|protocol is explained here]].
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To control the servos, you need to send things over the bus to the PCB. The [[spi_servo 1.0_protocol|protocol is explained here]].
  
 
== The software ==
 
== The software ==

Revision as of 16:20, 11 May 2012

The SPI_Servo PCB
The Servo PCB (SPI version photographed)

This is the documentation page for the SPI_servo and I2C_SERVO boards.

Overview

This module enables you to easily control upto 7 servomotors over an SPI or I2C interface, while needing minimal resources from your CPU. The PCB is equipped with two SPI or I2C connectors, so daisychaining multiple SPI or I2C modules is possible.
This allows you to control a chain of boards with only 4 data lines (MOSI, MISO, SS and SCK) for SPI or two lines (SDA, SCL) for I2C. This is not only pin-saving, but is is also possible do daisy-chain multiple modules (we will be releasing even more boards with other functions in the very near future)!
The board can be used with all microcontrollers, such as the Atmel AVR, Arduino/Freeduino boards, Microchip PIC, Raspbery PI etcetera.

For small servos, the power supplied by the SPI or I2C connector is enough. However current surges of up to a whole ampere are easily achieved even when two or three smaller servos need to move simultaneously. For larger servos however, the voltage drop may be to high. We suggest conneting an auxillary 5V power source to the PCB, and move the jumper.

External resources

Datasheets

The CPU: http://www.atmel.com/dyn/resources/prod_documents/doc8006.pdf

Additional software

Related projects

Pinout

The pinout is standard for servo-motors; Pin 1 is GND (near the edge of the board) Pin 2 is VCC (5V) Pin 3 is data

LEDs

The only LED is a power-LED.

Jumper settings

Solder jumper (on bottom layer): ICSP-Enable. CAUTION! Pin 1 and 2 are connected by a narrow PCB track. Cut this if you want to change this jumper setting.
1-2: Default: Both SPI connectors connected in parallel.
2-3: ICSP enabled; programming the MCU over the 6-pin connector. This connector may be marked SPI1 or SPI3 (near the edge of the board, furthest from the CPU.)

Programming

To control the servos, you need to send things over the bus to the PCB. The protocol is explained here.

The software

Default operation

Future hardware enhancements

Future software enhancements

Changelog

1.2

  • Added jumper/power connector for (external) servo power.

1.0

  • Initial public release