NAND Flash Programming
A critical step in the manufacturing of embedded devices is to program the final application image into the non-volatile storage device, which is typically a Flash device. Some companies opt for pre-programming the part to save time at the Contract Manufacturer (CM), but many others have to program the part on the factory floor with the very latest image.
As more embedded applications rely on Android, Linux, and other operating systems – the final application image is often hundreds of megabytes in size. This often leads to a design decision to use NAND Flash as the primary non-volatile storage. A typical programming rate of NAND Flash memory is 10 MB/s, but the typical file transfer rate of Serial is 90-100 Kb/s and the typical file transfer rate of a JTAG interface is 200-300 Kb/s. Using a faster file transfer interface is critical to realizing faster programming times, and reducing manufacturing time.
VTOS Program NAND™
The primary goals of Kozio’s product for NAND programming are ease of integration into the manufacturing process, reducing time spent per manufactured device, and improving yield. Using a JTAG interface for communicating with a target device provides a way to communicate with a board that has not been loaded with a boot loader or operating system. Although this is a great communications channel, and often easy to use in manufacturing, it is not the fastest interface for file transfers.
The Kozio solution uses prebuilt software that runs on the target device without modification or porting. This solution provides a client running on the target device, and a server running on a networked computer, to transfer files over Ethernet for faster overall programming times. This solution takes advantage of buffering, fast file transfers, and optimal programming to reduce the total time to program large files.
The Kozio solution also provides an API allowing it to be integrated with any test executive, and allowing faster integration into the manufacturing process. This software solution is in its third generation and has proven to increase yields for customers using VTOS Program in manufacturing.
In order to characterize the cost savings using the Kozio solution, an Excel spreadsheet was created. The spreadsheet allows you to update the number of devices you will be producing per year, the size of the image being programmed, and the operator cost per minute. The second set of key input parameters is the file transfer or interface speed, the programming speed, and product costs. In this example, we used a efficiency rate of 30% – meaning that we are only able to transfer a file at 30% of the maximum throughput.
The following screen shot provides a capture of cost savings of using VTOS Program NAND over a JTAG interface. The formulas used take into account how many stations are required, and the total cost of manufacturing a device for five years. Click on the image to enlarge.