lpcware

WriteEP USB

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by storm9113 on Thu Oct 23 02:50:51 MST 2014
Hi all,

I am working on USB transfert on LPC4357.

I used the cdc_vcom example and removed all the vcom part to only keep the init of USB and handlers and then call a WriteEP to send data to Host.

I am able to send the data but I wanted to ask 2 questions about the USB mechanism.

1- In LPCopen is this USB mechanism using CPU or is the USB module working by it own without needing CPU ressources  ?

2- If it is using CPU, how to know when a transfer is complete, I guess a completion interrupt comes out ?

For example if I try to send by this way

while(1){
g_pUsbApi->hw->WriteEP (g_hUsb, EP, (uint8_t*)buf1, size1);
__WFI();
g_pUsbApi->hw->WriteEP (g_hUsb, EP, (uint8_t*)buf2, size2);
__WFI();
}


Using this methode I can receive data on host but some data is missing.

- Am I using a wrong method ? Or do I just made an error in writeEP function ?


Thank you very much

Outcomes