python读取二进制文件写入到txt

import os
os.chdir(r'C:\Users\Usmart\Desktop\file_test')
fp=open("index.dat",'rb') #以只读二进制文件打开
data = fp.read()
fp_txt=open("text.txt",'w') #以只读二进制文件打开
for tmp in data:
    writedata ='{}'.format(hex(tmp))
    fp_txt.write(writedata)  
    fp_txt.write("  ") 
fp.close()