Launchpad Motor Expander V1.1 Last Modified Sept. 12, 2011 – launchpadbling.com – Copyright 2011

Absolute Maximum Ratings:

If Toggle Switch S1 and U2 / U3 voltage regulators are installed:

Minimum Vin Voltage = 7VDC

Maximum Continuous Vin Voltage = 25VDC

Maximum Short Duration Vin Voltage = 35VDC

Peak Short Duration Motor Output Current = 3 Amps each

Peak Continuous Output = 2 Amps each

If Toggle Switch S1 and U2 / U3 voltage regulators are omitted (external logic voltage required):

Minimum Vin Voltage = Launchpad Output High Voltage + 2.5VDC

Maximum Continuous Vin Voltage = 46VDC

Maximum Short Duration Vin Voltage = 50VDC

Peak Short Duration Motor Output Current = 3 Amps each

Peak Continuous Output = 2 Amps each

Theory of Operation:

The central component of this board is the L298 Motor Controller (U1). Using the digital logic outputs of

the Launchpad, the L298 is able to provide forward and reverse capabilities of two motors using the H-

Bridge principal. An explanation of H-Bridge motor control can be found here:

http://en.wikipedia.org/wiki/H_bridge

Simply altering the Launchpad outputs P1.1, P1.2, P1.3 & P1.4 will cause corresponding outputs on the

high-power motor outputs as follows:

P1.1 P1.2 Motor 1 P1.3 P1.4 Motor 2

Low Low OFF Low Low OFF

High Low Forward High Low Forward

Low High Reverse Low High Reverse

High High OFF High High OFF

If the DC motors are rotating in the wrong direction, simply reverse the positive and negative terminals.

Also on-board are two voltage regulators and a convenient toggle switch. The battery / voltage input is

fed directly into these voltage regulators to provide on-board 3.3VDC and 5VDC. There is no need for

additional external voltage sources.

Parts List & Description:

C1 & C3: 0.1uF Ceramic Capacitor, Marked ‘104’ (Digikey P/N 399-4151-ND)

C2 & C4: 0.33uF Ceramic Capacitor, Marked ‘334’ (Digikey P/N 399-4299-ND)

- C1-4 are used to smooth input and output voltages of voltage regulators U2 & U3

R1 & R2: 10k Carbon Resistor, 1/4W, 5%, Marked BROWN-BLACK-ORANGE (Digikey P/N 10KQBK-ND)

- R1 & R2 are pull-up resistors used to pull the enable pins of U1 default active high

D1 – D8: Schottky Diode, Fast Recovery, 1N5818-TP (Digikey P/N 1N5818-TPCT-ND)

- Diodes D1-8 are flyback diodes intended to protect U1 against overcurrent / overvoltage caused

by the inductive motor outputs

J1 & J2: 10-position standard square header, 0.100” pitch (Digikey P/Ns 609-3465-ND, & S7043-ND)

- J1 and J2 male headers mounted on the underside provide the interconnection between the

Launchpad and the expander board

- The female headers mounted on the top side provide a connection point for custom circuits OR to

connect to more expansion boards

J3: 2-position standard square jumper, 0.100” pitch (Digikey P/Ns 609-3465-ND, & 3M9580-ND)

- J3 jumper connects the 3.3VDC power from the voltage regulator U3 to the Launchpad below.

Remove this jumper when powering the Launchpad via a USB cable and / or during programming

J4: 2-position standard square jumper, 0.100” pitch (Digikey P/Ns 609-3465-ND, & 3M9580-ND)

- J4 controls the 5V power to the logic circuits of U1. Remove this jumper to disable motor controls.

J5: 4-position standard square jumper, 0.100” pitch (Digikey P/N S7037-ND)

- Provides a connection location to disable the individual motor outputs. Connect the outermost

pins (ground) to one or two of the innermost pins to disable motor output(s)

J6: 16-position (8x2) standard square jumper, 0.100” pitch (Digikey P/N S7111-ND)

- Provides a convenient connection location to connect Ground, +3.3VDC, +5.0VDC and Vin voltage

to custom circuits in the prototyping section of the board

U1: IC Motor Driver, (Digikey P/N 497-1395-5-ND)

- Through the use of an internal H-Bridge, this IC translates the low power logic output of the

Launchpad to the power outputs to the motors

U2: 5-Volt Linear Voltage Regulator (Digikey P/N LM7805ACT-ND)

- Uses the Vin input voltage and regulates it to 5VDC to supply the logic circuits of U1

U3: 3.3-Volt Linear Voltage Regulator (Digikey P/N 296-21633-5-ND)

- Uses the Vin input voltage and regulates it to 3.3VDC to supply power to the Launchpad

Screw Terminal Strip: 6-position leaf spring screw terminal (Digikey P/N ED2229-ND)

- Connection point for the battery / power supply inputs and two DC motor outputs

S1: SPDT Toggle Switch (Digikey P/N EG2355-ND)

- Directly switches the power from the Vin pin of the screw terminal block

Assembly Instructions:

(NOTE: The parts and boards shown in these photos may not look exactly like yours)

1) Place and solder capacitors C1, C2, C3 & C4

2) Place and solder R1 & R2

3) Place and solder diodes D1 – 8. Make sure the white bands are facing in the correct direction.

C1 & C3 C2 & C4 Place Adjacent to U2 & U3

R1 & R2 Place Adjacent to U2

D1 – D8 Ensure Correct Polarity

4) Prepare, place and solder headers J1 through J6. Use cutters to break off the male pin headers

on J1 (10 pin) , J2 (10 pin) , J3 (2 pin) & J4 (2 pin)

5) Place a shorting jumper on each of J3 & J4

J3 J4 J5 J5

J1 & J2 (Top of Board) J1 & J2

(Underside) Cut / Break off

male headers

Solder male headers to the underside

of the board (note that both headers

take up the rightmost holes)

Place and

solder the

remaining

headers J3-6

J3 J4

Shorting

Jumpers

6) Place and solder Voltage Regulators U2 & U3

7) Place and solder motor driver U1

8) Place and solder the screw terminal block and toggle switch

9) To avoid possible clearance issues with the Launchpad below, trim all soldered terminals on the

underside of the board. Pay special attention to U1, S1 and the terminal block.

U2 (7805) U3 (78M33)

U1 (L298N)

Terminal Block

Switch

Trim all protruding through-hole pins to avoid clearance issues

10) Enjoy!

EN

A6

EN

B11

IN1

5

IN2

7

IN3

10

IN4

12O

UT

12

OU

T2

3

OU

T3

13

OU

T4

14

ISE

N A

1

ISE

N B

15

VS

4V

SS9

GN

D8

U1

L29

8NIN

1

2

OU

T3

GN

D

U2

LM

7805

AC

T-N

D

IN1

2

OU

T3

GN

D

U3

UA

78M

33C

KC

S

Vin

+5V

+3.3

V

GN

D

GN

D

GN

D

0.1u

F

C1

Cap

0.33

uF

C2

Cap

0.1u

F

C3

Cap

0.33

uF

C4

Cap

Vin

+5V

1 2 3 4 5 6 7 8 9 10

J1

1 2 3 4 5 6 7 8 9 10

J9

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P2.0

P2.1

P2.2

GN

DX

INX

OU

TT

EST

RST

P1.7

P1.6

P2.5

P2.4

P2.3

1 2 3 4 5 6 7 8 9 10

J2G

ND

XIN

XO

UT

TE

STR

STP1

.7P1

.6P2

.5P2

.4P2

.3

1 2 3 4 5 6 7 8 9 10

J8

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P2.0

P2.1

P2.2

1234

J5

GN

D

10K

R1+3

.3V

10K

R2

GN

DM1_

OU

T_P

M1_

OU

T_N

M2_

OU

T_P

M2_

OU

T_N

P1.4

P1.3

P1.2

P1.1

23 1

S1 SW-S

PDT

Vin

Vba

tt

D1

1N58

18

D4

1N58

18

D2

1N58

18

D3

1N58

18

D7

1N58

18

D6

1N58

18

D8

1N58

18

D5

1N58

18

GN

D

Vin

GN

D

Vin

12

34

56

78

910

1112

1314

1516

J6G

ND

GN

DG

ND

GN

D+3

.3V

+3.3

V+3

.3V

+3.3

V+5

V+5

V+5

V+5

VV

inV

inV

inV

in

1 2 3 4 5 6

J7V

batt

GN

D

12

J3+3

.3V

12

J4

Schematic: