Technical Success Stories: SD Card Application Software Optimizations
“We need the assistance of your Engineering Team to see why SD cards from another manufacturer are not working in our embedded application product.”
A manufacturer of hand held embedded computing devices got in touch with us to discuss an SD card failure that was causing a key product to freeze at an alarming rate. There were many customers reaching out reporting of data corruption or that the device did not work at all, and it started to become customer service challenge. The team working to address and fix the issue couldn’t get any support from their existing memory card supplier.
“The problem began a couple months back ago when our Product Development and Marketing Teams asked if we could extend the battery life of our top handheld device. This device was our best selling and most profitable product, and the lead device that several other models are based off. It was estimated that a power improvement could increase our market share, and be a strong unique value proposition allowing us to prove our products are better than the competition within the particular market.”
With some testing of the various ways the device can go through the battery power supply, we discovered that if we turned off the power to the SD card, we could reduce the overall power usage and extend the battery life between charges. The change was made to the application, some additional testing took place, and a power savings was achieved. The change was implemented on all units, providing the improved power rating.
The manufacturer of the handheld device contacted Delkin’s Customer Applications Team to work collaboratively and utilize Delkin’s engineering expertise to help come up with an innovative solution. The job got started right away to understand the usage model and capture bus activity between the host and the card. While as mix of he SD cards seemed to be corrupt, it was at a random interval, and we needed to understand why.
After further discovery, we learned that the SD card data corruption was a result of the power saving software change that was implemented just prior to launch. When the power to the card was “turned off”, the customer didn’t realize that the card could still draw just enough power to stay alive from leakage on signal pins. The little amount of power leakage was enough to keep the CPU alive and perform updating and data consolidation functions. When any type of write operation was attempted, the power immediately dropped and caused flash write errors.
Rather than simply “turning off” the power to the SD Card, Delkin recommended that the customer modify their application to drive each of the signal pins low, prior to switching off the power. Not only would this fix solve the data corruption issue, it also had the potential to save even more power by preventing power leakage after the main device power was turned off.
The customer thought it was excellent to see that altering a few things with the SD card could resolve the problem. They were able to make a quick update to their application software which updated the SD card functionality within the device. After the new code was loaded and tested, all units were updated within a few days and shipped out to their distributor base. Confidence was restored in the integrity and quality of their hand-held device, and they were able to rely on a renewed steady revenue stream from that product line.
It’s important to remember that a NAND flash memory card is a complex device that has an impact on the overall host device performance. It’s imperative that industrial OEMs work closely with their flash storage provider to choose the right type of NAND flash and maximize performance. In this scenario where degraded power was an issue, flash writes were misinterpreted and data was sent to the wrong location within the flash device. It took the close attention and testing by Delkin Engineers to help optimize the card application software, fix what was perceived as a data corruption issue, and reduce power consumption.
Lean on Delkin’s Technical Team
Have you had a problem with your host storage? The Delkin Customer Applications Team stands at the ready to be your trusted advisor for your host critical storage. We have solved hundreds of complicated host failures and look forward to understanding your usage model for flash based Rugged Controlled Storage.