Material

• Car/Robot: Ford F-150 (1:19) from NIKKO
• BTnode rev3 from ETH Zurich
• Quadruple Half-H Driver: L293D, alternatively SN754410
• 2xNPN transistors BC547
• 4x10k resistors

Disassembling the vehicle

The car has two motors. One is used for driving forward/backward using the rear wheels. The other motor is used for steering the front wheels left or right. We took the car apart and found a PCB with a lot of discrete components (transistors, resistors, ...) and a single IC, the PT8A978.

After some random guesses, we figured out that the IC is related to its "brother", the PT8A977 for which data sheets are available on the net. In short, the following pins are connected to to the amplification circuit:

• Pin 6: right
• Pin 7: left
• Pin 10: backward
• Pin 11: forward

We first removed the PT8A978 in order to control the motors but then decided to make our own driver.

Interface between motors and the BTnode3

We opted for building our own interface, so we replaced the original PCB with home-brew one based on the popular L293. The schema is shown in Figure 1.

http://bagira.ringwald.ch/picts/bagira_schema_thumb.png
Figure 1. Motor driver

The L293 contains two motor drivers. Each consists of four mosfets in an H-Bridge configuration. The control inputs are CMOS/TTL compatible, the output can provide output currents up to 1A per channel, at voltages from 4.5V to 36V.

Per driver, three control lines are needed: enable input and two input controls. The enable input turns the outputs of the driver on/off. For example, the enable line of the first driver, CHIP INHIBIT 1, controls outputs 1 and 2. Correspondingly, CHIP INHIBIT 2 of the second driver controls outputs 3 and 4. When a driver is enabled, its outputs become active and in phase with its input controls. The output lines can be set to GND or VCC individually.

We use the first driver to control the driving motor (forward/backward), and the second to control the steering motor (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of OUTPUT 1 using an NPN transistor. The same was done with OUTPUT 3 and OUTPUT 4. In this setup, we cannot actively brake, but only two control lines per motor are needed, see circuit schema.

Figure 2 depicts the BTnode connector pins. Tables 1 and 2 describe the mappings between BTnode pins and corresponding motor control.

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg
Figure 2. BTnode connector

Table 1. Mapping between BTnode pins and driving motor control lines

Table 2. Mapping between BTnode pins and steering motor control lines

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Material

• Car/Robot: Ford F-150 (1:19) from NIKKO
• BTnode rev3 from ETH Zurich
• Quadruple Half-H Driver: L293D, alternatively SN754410
• 2xNPN transistors BC547
• 4x10k resistors

Disassembling the vehicle

The car has two motors. One is used for driving forward/backward using the rear wheels. The other motor is used for steering the front wheels left or right. We took the car apart and found a PCB with a lot of discrete components (transistors, resistors, ...) and a single IC, the PT8A978.

After some random guesses, we figured out that the IC is related to its "brother", the PT8A977 for which data sheets are available on the net. In short, the following pins are connected to to the amplification circuit:

• Pin 6: right
• Pin 7: left
• Pin 10: backward
• Pin 11: forward

We first removed the PT8A978 in order to control the motors but then decided to make our own driver.

Interface between motors and the BTnode3

We opted for building our own interface, so we replaced the original PCB with home-brew one based on the popular L293. The schema is shown in Figure 1.

http://bagira.ringwald.ch/picts/bagira_schema_thumb.png
Figure 1. Motor driver

The L293 contains two motor drivers. Each consists of four mosfets in an H-Bridge configuration. The control inputs are CMOS/TTL compatible, the output can provide output currents up to 1A per channel, at voltages from 4.5V to 36V.

Per driver, three control lines are needed: enable input and two input controls. The enable input turns the outputs of the driver on/off. For example, the enable line of the first driver, CHIP INHIBIT 1, controls outputs 1 and 2. Correspondingly, CHIP INHIBIT 2 of the second driver controls outputs 3 and 4. When a driver is enabled, its outputs become active and in phase with its input controls. The output lines can be set to GND or VCC individually.

We use the first driver to control the driving motor (forward/backward), and the second to control the steering motor (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of OUTPUT 1 using an NPN transistor. The same was done with OUTPUT 3 and OUTPUT 4. In this setup, we cannot actively brake, but only two control lines per motor are needed, see circuit schema.

Figure 2 depicts the BTnode connector pins. Tables 1 and 2 describe the mappings between BTnode pins and corresponding motor control.

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg
Figure 2. BTnode connector

Table 1. Mapping between BTnode pins and driving motor control lines

Table 2. Mapping between BTnode pins and steering motor control lines

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We opted for building our own interface, so we replaced the original PCB with home-brew one based on the popular L293. The schema is shown in Figure 1.

Figure 1. Motor driver

Figure 2 depicts the BTnode connector pins. Tables 1 and 2 describe the mappings between BTnode pins and corresponding motor control.

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg
Figure 2. BTnode connector

Figure 2. outlines BTnode connector pins. Tables 1. and 2. outline mappings between BTnode pins, corresponding driver control inputs, and pin

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg
BTnode connector

Table 1. Mapping between BTnode pins and driving motor control lines

Table 2. Mapping between BTnode pins and steering motor control lines

Table 1. Mapping between BTnode pins and driving motor control lines

Table 2. Mapping between BTnode pins and steering motor control lines

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg

Mapping between BTnode pins and driving motor control lines

Mapping between BTnode pins and steering motor control lines

Mapping between BTnode pins and steering driver

| border=1 align=center width=50% |! ||! forward ||! backward || |inhibition PE3 || H || H || |ctrl. input PE6 || H || L ||

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg \\

We use the first driver to control the driving motor (forward/backward), and the second to control the steering motor (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of OUTPUT 1 using an NPN transistor. The same was done with OUTPUT 3 and OUTPUT 4. In this setup, we cannot actively brake, but only two control lines per motor are needed, see circuit schema.

The L293 contains two motor drivers. Each consists of four mosfets in an H-Bridge configuration. The control inputs are CMOS/TTL compatible, the output can provide output currents up to 1A per channel, at voltages from 4.5V to 36V.

Per driver, three control lines are needed: enable input and two input controls. The enable input turns the outputs of the driver on/off. For example, the enable line of the first driver, CHIP INHIBIT 1, controls outputs 1 and 2. Correspondingly, CHIP INHIBIT 2 of the second driver controls outputs 3 and 4. When a driver is enabled, its outputs become active and in phase with its input controls. The output lines can be set to GND or VCC individually.

We use the first driver to control the driving motor (forward/backward), and the second to control the steering motor (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of OUTPUT 1 using an NPN transistor. The same was done with OUTPUT 3 and OUTPUT 4. In this setup, we cannot actively brake, but only two control lines per motor are needed.

• 2xNPN transistors BC547
• 4x10k resistors

We use one driver to control the drive (forward/backward), and another to control steer (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of the OUTPUT 1 using a NPN transistor. The same we did with OUTPUT 3 and OUTPUT 4. With this setup, we cannot actively brake, but need only 2 control lines per motor.

• 2xPNP transistors, 4x10k resistors

Per driver, three control lines are needed: enable input and two input controls. The enable input turns the outputs of the driver on/off. For example, enable line of the first driver, INHIBIT 1, controls outputs 1 and 2. Correspondingly, INHIBIT 2 of the second driver controls outputs 3 and 4. When a driver is enabled, its outputs become active and in phase with its input controls. The output lines can be set to GND or VCC individually.

\\

We use one driver to control the drive (forward/backward), and another to control steer (left/right). To save on microcontroller lines, we connected the OUTPUT 2 control line with the inverted output of the OUTPUT 1 using a PNP transistor. The same we did with OUTPUT 3 and OUTPUT 4. With this setup, we cannot actively brake, but need only 2 control lines per motor.

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg \\

Per driver, three control lines are needed: enable input and two input controls. The enable input turns the outputs of the driver on/off. For example, enable line of the first driver, Inh1, controls outputs 1 and 2. Correspondingly, Inh2 of the second driver controls outputs 3 and 4. When a driver is enabled, its outputs become active and in phase with its input controls. The output lines can be set to GND or VCC individually.

We use the two input controls to control the drive and the steering motors respectively. To save on microcontroller lines, we connected the second output control line with the inverted output of the first one using a PNP transistor. With this setup, we cannot actively brake, but need only 2 control lines per motor.

The L293 contains 2 x 4 mosfets in an H-Bridge configuration. The control inputs are CMOS/TTL compatible, the output can provide output currents up to 1A per channel, at voltages from 4.5V to 36V.

Per driver, three control lines are needed. One control line (V_inh) turns the output of the driver on/off. When turned on, the two output lines can be set to GND or VCC individually.

We opted for building our own interface, so we replaced the original PCB with home-brew one based on the popular L293. The schema is shown in Picture below.

The L293 contains 2 x 4 mosfets in an H-Bridge configuration. The control inputs are CMOS/TTL compatible, the output can provide up to X Volts at Y mA (.. get real values.. :)

Per driver, 3 control lines are needed. One output enable line turns the output drivers on/off. When turned on, the two output lines can be set to GND or VCC individually.

To save on microcontroller lines, we connected the second output control line with the inverted output of the first one using a PNP transistor. With this setup, we cannot actively brake, but need only 2 control lines per motor.

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg \\

• Car/Robot: Ford F-150 (1:19) from NIKKO

The car has two motors. One is used for driving forward/backward using the rear wheels. The other motor is used for steering the front wheels left or right. We took the car apart and found a PCB with a lot of discrete components (transistors, resistors, ...) and a single IC, the PT8A978.

After some random guesses, we figured out that the IC is related to its "brother", the PT8A977 for which data sheets are available on the net. In short, the following pins are connected to to the amplification circuit:

• Pin 6: right
• Pin 7: left
• Pin 10: backward
• Pin 11: forward

We first removed the PT8A978 in order to control the motors but then decided to make our own driver.

Interface between motors and the BTnode3

We opted for building our own interface, so we replaced the original PCB with home-brew one. The schema is shown in Picture below.

http://bagira.ringwald.ch/picts/bagira_schema_thumb.png

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg \\

http://bagira.ringwald.ch/picts/btnode_rev3.22_debug_j2.jpg
BTnode connector

\\

\\

\\

\\

Interface between motors and the BTnode3

We opted for building our own interface, so we replaced the original PCB with home-brewed one. The scheme is shown in Picture bellow.

http://bagira.ringwald.ch/picts/bagira_schema_thumb.png \\

http://bagira.ringwald.ch/picts/bagira_schema_thumb.png

http://bagira.ringwald.ch/picts/bagira_schema.png

http://bagira.ringwald.ch/picts/bagira_schema.png

[[http://http://bagira.ringwald.ch/picts/bagira_schema.pdf

| link text]]

http://bagira.ringwald.ch/picts/bagira_schema.png
Motor driver

• Quadruple Half-H Driver: L293D, alternatively SN754410

• Quadruple Half-H Driver: L293D, alternatively SN754410 Quadruple Half-H Driver

\\

• L293D Quadruple Half-H Drivers, alternatively: SN754410 Quadruple Half-H Driver

• BTnut (and Ethernut a.k.a. Nut/OS)

• AVR toolchain

• lightblue (on Mac it requires XCode with support for the 10.4u.SDK: in project preferences you need to select gcc4.0)

• L293D Quadruple Half-H Drivers
• alternatively: SN754410 Quadruple Half-H Driver

Material

Hardware

Software

• avr tools
• btnut
• lightblue (on Mac it recquires xcode with support for SDK4: in project preferences you need to set gcc4.0)

Disassembling the vehicle

Robot has two motors. One motor is used for forward/backward moving using the rear wheels. The other motor is used for stearing of the front wheels to left or right. We took robot apart and found a PCB with a lot of discrete components (transistors, resistors, ...) and a single IC, the PT8A978.

After a while and random guessing we figured out that the IC could be related to its "brother", the PT8A977 for which the data-sheets are available. In short, the following pins are input to the amplification circuit:

• pin 6: right
• pin 7: left
• pin 10: backward
• pin 11: forward

One could use these lines from the IC and directly connect them to the amplification circuit to a microcontroller.

We opted for building our own interface, so we replaced the PCB with home-brewed one. The scheme is shown in Picture bellow.

• robot: Ford F-150 (1:19) from NIKKO
• BTnode rev3 from ETH Zurich

• SN754410 Quadruple Half-H Driver

Robot has two motors. One motor is used for forward/backward moving using the rear wheels. The other motor is used for stearing of the front wheels to left or right.

• robot: Ford F-150 (1:19) from NIKKO, 30.00 Euro
• BTnode rev2 from ETH Zurich
• Atmel development tools

After getting a toy we wanted to figure out how to connect its control board to a BTnode. Robot has two motors. One motor is used for forward/backward moving using the rear wheels. The other motor is used for stearing of the front wheels to left or right.