Arduino mega 2560+usb host shield+ motorshield

Hello users, i have actually a supply trouble with arduino motor shield:

When i use the 3 cards in same time, the channel A of the motor shield works, this channel supply a dc motor. The channel B do not deliver any power.

my system is compose of:

an 12Vdc power supply (Max current limited to 2A) arduino mega 2560 arduino usb host shield arduino motor shield

When i use [u]only[/u] the arduino mega 2560 and the motor shield ,i can use the 2 channel of the motor shield ( A and B) , [u]Channel B deliver power here.[/u]

i use a simple programm like it: void setup pinMode (3 , OUTPUT); channel A PWM pinMode (12 , OUTPUT); channel A DIRECTION pinMode (11 , OUTPUT); channel B PWM pinMode (13 , OUTPUT); channel B DIRECTION

void loop: digitalWrite (12, HIGH); analogWrite (3,190); pwm to 190 because i supply motor around 9V

digitalWrite (13, HIGH); analogWrite (11, 190); Brake supply

Arduino mega 2560 + usb host shield + motor shield are supposed to works together.

Pin use for motor shield 3,11,12,13 pin use for usb host shield 50,51,52 with mega board 2560 ( thanks to ICSP Connector)

"" 10,11,12,13 with the arduino UNO

Bonjour; je suis de dieppe et aussi concepteur/programmeur sur carte arduino. Peut on discuté de ton soucis par mail? ecris moi à Cdt Joël