如何保护Excel中的单元格，但允许VBA脚本对其进行修改?

I am using Excel where certain fields are allowed for user input and other cells are to be protected. I have used Tools Protect sheet, however after doing this I am not able to change the values in the VBA script. I need to restrict the sheet to stop user input, at the same time allow the VBA code to change the cell values based on certain computations.I am using Excel where certain fields are allow