NP-41 Emulator (may be)

[Chris Chung]

About the newer firmware and another evaluation unit.

I had received my 4 lcd modules and I had Etienne's unit built but want to hold it for a few days before shipping it out. Mainly the sleep power consumption issue is not completely resolved and if it is hardware related, it's better to fix it before shipping it out.

I checked the sleep mode power consumption and found that I had intermittent power problems. Usually I would get about 7uA during sleep, so for a 200mAh CR2032, we can sleep for about 1200 days. But sometimes when I put the unit to sleep it ends up at 230-240uA, which is 30+ times the norm.

I suspected it's the LCD module failed to get into sleep mode, as per specification it's active power is about 200uA and when sleep the datasheet said 4uA max.

I altered the code to send "sleep" command sequence twice, plus add some timing to allow the SPI bus ample time to finish communicating. Which improved the odds and I thought I had solved it. Still after the fix I got again some instances that the sleep power is excessive at 200+uA. So more debugging on this.

The main addition in this new firmware is that a bootloader is available so that future firmwares can be loaded via a USB-Serial cable. I will describe to procedure in a separate post. The USB-Serial cable is also used to load ROM files of up to 16K.