2 replies to this topic

[weihong1988]

Hi everyone,

After wearing out the F5 key on my keyboard and still not able to purchase a coptercontrol board. I have decided to build my own.

I have been able to source most of the parts locally from element14 Singapore. However, some parts are not available. Can I make the following subsitutions?

1. Change the 4Mbit SPI flash from W25X40BVSNIG (Winbond) to S25FL004K0XMFI011 (Spansion)
Datasheet: http://sg.element14....jsp?sku=1861624

I have skimmed through the datasheet, both have the same package and pinouts. Their opcode ID are nearly the same, for basic functions like erase page, write page, read page etc. The differences is that the Status register for the Spansion part has more bit entries compared to the Winbond part, and the Spansion has more opcodes

Do you guys think I can use this chip instead? My guess is that flash chips should be nearly the same and interchangeable. Do anyone have a full list of function opcodes used in the CC flash write routine? Is the volatile status register programmed anywhere in the code?

2. Change the crystal from 8MHz to 12MHz.

Amazingly, I cannot find a 8MHz crystal in 5mm x 3.2mm package. Can I use a 12MHz crystal and drop the PLL multiplier on the STM32 so that the final PLL clock still runs at 72MHz? Any gotchas I should be aware of?

3. Peabody mentions that one of the parts have a high failure rate. Any hints so I can order more parts?

I am guessing the 2 axis gyro based on a simple google search ie. "ComponentName problems" and seeing the number of hits. Is my guess correct?

Total BOM + PCB will be around $87 SGD per piece (Making 3) , so I would say it is quite reasonable to make your own.

[b0ba]

Strange enough price has element14 for IDG-500....

[weihong1988]

Dont buy the gyros from element14. They are expensive. Get them from CDIweb. Their prices are more reasonable.