Question in Propeller Education Kit Labs (Fundamentals) Version 1.1

Rich_W8VK

Hello All!
···· Page 169 under the Sub Heading: Calculating FRQ and PLLDIV Given a PLL Frequency!
···· Calculation 4) The FRQ Register Value! I don't see the answer of 322_122_547
···· Can someone Please, tell me how to arrive at this answer?
Thanks!


Rich_W8VK

Graham Stabler

Hello,

I get the same answer as the book, there is a .2 on the end but this is just removed. If you don't get the same answer then you are doing something wrong with your calculator.

FRQ = 6Mhz . (2^ 32)
             80Mhz

I have put the 2^32 in brackets as the power of 32 should be calculated only on the 2 and should be 4294967296 when it says 6Mhz you would replace that with 6000000 and likewise 80Mhz with 80000000 but in fact because the factor of 1 million is common to both of them it cancels, the calculation becomes

FRQ = 6*(4294967296)/80 = 322_122_547.2 and the .2 is removed because we deal only with integers.

Graham

p.s. The large green font is really not required and will make longer posts awful to read.

Post Edited (Graham Stabler) : 2/20/2010 7:58:32 PM GMT

Rich_W8VK

Graham,
···· Thanks! I had the 2 to the 32 power right! Ha!

Rich_W8VK