PDA

View Full Version : Two random questions



Chad George
03-24-2009, 06:38 AM
1. Can the propeller use a 12Mhz crystal in x8 mode for 96MHz? I'm pretty sure its outside the datasheet specs, but will it work under some reasonable (but possible restricted) voltage and temp ranges.

2. Is holding the reset input low an acceptable "sleep" mode?

Beau Schwabe (Parallax)
03-24-2009, 07:11 AM
Chad George,

1) 12MHz might be pushing it

2) I don't see a problem as long as you have some means to come out of sleeping.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Timothy D. Swieter
03-24-2009, 07:19 AM
Two random answers:

1. 42
2. It depends on the angle of the axis of rotation of the Earth.

(sorry - trying to be fun).

Seriously, other users have run the Propeller at 96MHz., but they did it with a 6MHz. crystal and a PLL setting of 16. Running at 96MHz. is out of the range of the specs of the design, but it can be done. There was a product from 4D Systems - the uOLED-96-PROP. The System had an 8 MHz. crystal in it and some of those system worked when run with a PLL 16, but the majority of the systems I believe only worked with a PLL of 8. There was a lot of discussion on that in other threads.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Timothy D. Swieter, E.I.
www.brilldea.com (http://www.brilldea.com) - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
www.tdswieter.com (http://www.tdswieter.com)

Paul Baker
03-24-2009, 10:49 AM
answer to first question is no, the internal PLL always multiplies by 16 which means it will be operating at 192 MHz which is beyond the maximum rating for it. Use a 6MHz crystal if you want 96MHz operation.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Paul Baker (mailto:pbaker@parallax.com)