本帖最后由 easylwl 于 2013-4-22 17:10 编辑
用STM32F207VC 开发 usb设备 BULK传输 ,
使用了两个端点 IN 端点 0X82 和 OUT端点 0X03 ,端点的最大包长度都是 64 字节
问题是 ,FIFO的大小应该怎样设置呢?
ST官方代码包有这个注释:
/*******************************************************************************
* FIFO Size Configuration in Device mode
*
* (i) Receive data FIFO size = RAM for setup packets +
* OUT endpoint control information +
* data OUT packets + miscellaneous
* Space = ONE 32-bits words
* --> RAM for setup packets = 10 spaces
* (n is the nbr of CTRL EPs the device core supports)
* --> OUT EP CTRL info = 1 space
* (one space for status information written to the FIFO along with each
* received packet)
* --> data OUT packets = (Largest Packet Size / 4) + 1 spaces
* (MINIMUM to receive packets)
* --> OR data OUT packets = at least 2*(Largest Packet Size / 4) + 1 spaces
* (if high-bandwidth EP is enabled or multiple isochronous EPs)
* --> miscellaneous = 1 space per OUT EP
* (one space for transfer complete status information also pushed to the
* FIFO with each endpoint's last packet)
*
* (ii)MINIMUM RAM space required for each IN EP Tx FIFO = MAX packet size for
* that particular IN EP. More space allocated in the IN EP Tx FIFO results
* in a better performance on the USB and can hide latencies on the AHB.
*
* (iii) TXn min size = 16 words. (n : Transmit FIFO index)
* (iv) When a TxFIFO is not used, the Configuration should be as follows:
* case 1 : n > m and Txn is not used (n,m : Transmit FIFO indexes)
* --> Txm can use the space allocated for Txn.
* case2 : n < m and Txn is not used (n,m : Transmit FIFO indexes)
* --> Txn should be configured with the minimum space of 16 words
* (v) The FIFO is used optimally when used TxFIFOs are allocated in the top
* of the FIFO.Ex: use EP1 and EP2 as IN instead of EP1 and EP3 as IN ones.
*******************************************************************************/
看不懂??
我的设置为:
#ifdef USB_OTG_FS_CORE
#define RX_FIFO_FS_SIZE 128
#define TX0_FIFO_FS_SIZE 32
#define TX1_FIFO_FS_SIZE 0
#define TX2_FIFO_FS_SIZE 128
#define TX3_FIFO_FS_SIZE 0
可是IN发送不了??
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