[低價USB DAQ卡計畫] Microchip c18: USBGenWrite()與USBGenRead() @ 魚的方舟圖形語言的世界 - LabVIEW & Arduino & Python工作室 - 新網站https://labview-tech.blogspot.com/

在USB 資料Packet的傳輸中,

有兩個函數會被使用到, 分別是USBGenWrite()與USBGenRead(),

我們從help檔中分別來看這兩個函數,

1. 首先是USBGenWrite(),

裡面要注意兩個變數 : data與len,

data 是只要傳送的資料內容, 由Byte陣列構成 , 而len是指要傳送的陣列長度,

#define USBGenWrite(ep,data,len) USBTxOnePacket(ep,data,len)

Description

This function sends the specified data out the specified endpoint and returns a handle to the transfer information.

Typical Usage:

Copy Code

//make sure that the last transfer isn't busy by checking the handle
if(!USBHandleBusy(USBGenericInHandle))  --> input handle是否忙碌中?
{
    //Send the data contained in the INPacket[] array out on
    // endpoint USBGEN_EP_NUM
    USBGenericInHandle = USBGenWrite(USBGEN_EP_NUM,(BYTE*)&INPacket[0],sizeof(INPacket));
}

Preconditions

None

Parameters

Parameters	Description
ep	the endpoint you want to send the data out of
data	pointer to the data that you wish to send
len	the length of the data that you wish to send

Return Values

Return Values	Description
USB_HANDLE	a handle for the transfer. This information should be kept to track the status of the transfer

2. 再來是 USBGenRead() , 變數與USBGenWrite()大同小異,

注意的是:

USBGenWrite()的data使用INPacket, 而USBGenRead()使用是OUTPacket, 資料長度為64 byte.

#define USBGenRead(ep,data,len) USBRxOnePacket(ep,data,len)