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USB not recognised by computer

 
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BM92



Joined: 04 Oct 2013
Posts: 18

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USB not recognised by computer
PostPosted: Wed Jan 29, 2014 1:46 pm     Reply with quote
I am using a PIC32MX795F512L in device mode but cannot get it to connect.

So here is a step by step of what is happening to aid with any help people can give.

Before i attach USB cable:

3.3v at Vusb (RF6)
3.3v at Vbus (RF7)
0V at D+ (RG2)
0V at D- (RG3)

After i attach USB

3.7v at Vusb (RF6)
5v at Vbus (RF7)
0V at D+ (RG2)
0V at D- (RG3)

I am unsure why Vusb is getting a voltage increase when it is attached to nothing but a capacitor and 3.3v
The computer is not recognizing that a device is attached and D+ and D- show no activity on oscilloscope

My setup is as follows:

VCC (pin 1) -> vbus (RF7) with 4.7uF cap
GND (pin 4) -> GND
D+ (pin 3) -> RG2
D- (pin 2) -> RG3
3.3v via 100nF cap to Vusb (RF6)
Wire from Vcc to RB5 to trigger USB_BUS_SENSE

i am using interrupt mode and the main part of my code can be seen below

Code:
int main(void)
{   
    InitializeSystem();

    USBDeviceAttach();

    while(1)
    {
        ProcessIO();       
    }//end while
}//end main


Code:
static void InitializeSystem(void)
{
    AD1PCFG = 0xFFFF;
    SYSTEMConfigPerformance(60000000);

    #if defined(USE_USB_BUS_SENSE_IO)
    tris_usb_bus_sense = INPUT_PIN; // See HardwareProfile.h
    #endif

    #if defined(USE_SELF_POWER_SENSE_IO)
    tris_self_power = INPUT_PIN;   // See HardwareProfile.h
    #endif

    UserInit();
   
    USBDeviceInit();   //usb_device.c.  Initializes USB module SFRs and firmware
                   //variables to known states.
}//end InitializeSystem


Code:
void USBDeviceAttach(void)
{
    //if we are in the detached state
    if(USBDeviceState == DETACHED_STATE)
    {
        if(USB_BUS_SENSE == 1)
        {
           //Initialize registers to known states.
            U1CON = 0;         
   
            // Mask all USB interrupts
            U1IE = 0;                               
   
            //Configure things like: pull ups, full/low-speed mode,
            //set the ping pong mode, and set internal transceiver
            SetConfigurationOptions();
   
            USBEnableInterrupts();  //Modifies global interrupt settings
   
            // Enable module & attach to bus
            while(!U1CONbits.USBEN){U1CONbits.USBEN = 1;}
   
            //moved to the attached state
            USBDeviceState = ATTACHED_STATE;
        }
    }
}


Theses are the main snippets of code i believe to be important to get it to connect. Is there any reason why my PC does not recognise my device at all.
Ttelmah



Joined: 11 Mar 2010
Posts: 19563

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PostPosted: Thu Jan 30, 2014 1:42 am     Reply with quote
That is the MicroChip USB stack, not CCS. Go and ask in their forum.
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