使用usb，出现非对齐异常

发布于 2018-12-10 17:03:17 浏览：2355 订阅该版

打印信息：

\ | /
- RT -     Thread Operating System
 / | \     3.1.0 build Dec 10 2018
 2006 - 2018 Copyright by rt-thread team
lwIP-2.0.2 initialized!
psr: 0x61000000
r00: 0x80080e34
r01: 0x80041288
r02: 0xffffffff
r03: 0x00000000
r04: 0x800412a0
r05: 0x800414c4
r06: 0xdeadbeef
r07: 0xdeadbeef
r08: 0x80080e8c
r09: 0x80080e34
r10: 0xdeadbeef
r11: 0xdeadbeef
r12: 0x80023309
 lr: 0x80024907
 pc: 0x800244d0
hard fault on thread: main

thread pri  status      sp     stack size max used left tick  error
------ ---  ------- ---------- ----------  ------  ---------- ---
usbd     8  suspend 0x000000ac 0x00001000    04%   0x00000014 000
tcpip   10  suspend 0x000000c8 0x00000400    19%   0x00000014 000
etx     12  ready   0x00000048 0x00000400    07%   0x00000010 000
erx     12  ready   0x00000048 0x00000400    07%   0x00000010 000
tidle   31  ready   0x00000048 0x00000100    28%   0x00000020 000
main    10  ready   0x000000b4 0x00000800    14%   0x00000011 000
usage fault:
SCB_CFSR_UFSR:0x100 UNALIGNED

目的：想把u盘接usb口，然后在u盘里放文件
平台：rt1020

配置：
/* Using USB */

#define RT_USING_USB_DEVICE
#define RT_USBD_THREAD_STACK_SZ 4096
#define USB_VENDOR_ID 0x0FFE
#define USB_PRODUCT_ID 0x0001
#define _RT_USB_DEVICE_NONE
#define RT_USB_DEVICE_NONE
#define RT_USING_EHCI0_AS_DEVICE

执行到下面这句话开始报错：
![TIM截图20181210165809.png](/uploads/201812/10/165931zxay4yl45hl45zeh.png)

问题：
1 为什么会出现字节不对齐？一直用的4字节对齐
2 #define RT_USING_EHCI0_AS_DEVICE 注释掉以后，没有报错，u盘也没有初始化成功