Doubt with the ADC convertion time in MPC5604B

[jaquense]

Hi, someone knows how to configure the CTR register to make the ADC convertion time in 1 us?. with the analog clock in 32MHZ

In the examples; they configured with this value: 0x00008606. Making the calculations with this configuration we have:

40*Tck = 40 * 1/32 = 1.25 us

And the result is not 1 us……..

In the reference manual says that the minimum convertion time was 1 us, but in the page 728 under the table says "“The ADC minimum conversion time at 60 MHz frequency is 39 * Tck; that corresponds to 650 ns". This is contradictory, isn't it?

Can you help me?

Best Regards,

[TomE]

Which version of the Reference Manual are you looking at? I'm looking at "MPC5604B/C Microcontroller Reference Manual, Rev. 8". I note there's a Rev 8.1 dated 5/25/2012 on Freescale's web site. is that the one you're looking at? In the one i have I can't see any mention of 1us conversion of 60MHz operation in the ADC chapter (which is on pages 591 to 629, quite different to yours). "Table 25-3. Max/Min ADC_clk frequency and related configuration settings at 5 V / 3.3 V for ADC_0" seems to give the best summary, with a maximum clock speed of 32MHz and a minimum conversion time of 1.156us taking 37 clocks. I've found where there are apparent contradictions in the manual, it is sometimes the difference between what the specific module is capable of (given that it can be used in different micros), and what it can do in a specific micro, with specific clocking and other bus limitations. Just as the silicon modules are used in different chips, their associated chapters are dropped into the manuals for a chip and then edited to describe what they can do in that chip. Sometimes there are cut-and-paste errors in this editing, often fixed in later revisions of the manual. The Revision History lists differences between Revs 7 and 8 or the manual, including changes to the ADC section. Tom