M. Kerhuel,

we use the PIC mechanism for two-speed start-up, and we would very

much like this to be supported in the block-set. The necessary strange invocations

for the dsPIC33F series follow (taken from the Microchip manual section 70186b.pdf).

I believe it's similar for other PIC variants, but have not checked.



The extra configuration settings (in _FOSC()) are

FCKSM_CSECME Both enabled

FCKSM_CSECMD Only clock switching enabled

FCKSM_CSDCMD Both disabled (default, as the block-set does at present)



Bernard Leak.





Just *after* setting PLLFBD and CLKDIV as at present, the oscillator mode can be

switched over as follows:



;Place the New Oscillator Selection (NOSC=0b101) in W0

MOV #0x15,w0

;OSCCONH (high byte) Unlock Sequence

MOV #OSCCONH, w1

MOV #0x78, w2

MOV #0x9A, w3

MOV.B w2, [w1] ; Write 0x78

MOV.B w3, [w1] ; Write 0x9A

;Set New Oscillator Selection

MOV.B w0, [w1]

; Place 0x01 in W0 for setting clock switch enabled bit

MOV #0x01, w0

;OSCCONL (low byte) Unlock Sequence

MOV #OSCCONL, w1

MOV #0x46, w2

MOV #0x57, w3

MOV.B w2, [w1] ; Write 0x46

MOV.B w3, [w1] ; Write 0x9A

; Enable Clock Switch

MOV.B w0, [w1] ; Request Clock Switching by Setting OSWEN bit

wait:

btsc OSCCONL, #OSWEN

bra wait

Dear Bernard,



I am not sure to understand what your need is.

Do you want to manually "change" the clock source within the program (i.e. add a block to do it in the simulink model ?)





Or do you want to use the "Two Speed Start-up" as it is described from the 70186b.pdf doc you mentioned page 7-31 ?

In this last case, my understanding of this page is the following:

The include file of dsPIC33 has the following parameters :



; Two-speed Oscillator Startup :

; IESO_OFF Disabled

; IESO_ON Enabled



The blockset always set the two speed startup to off (IESO_OFF).



If I add an option so as to configure it to (IESO_ON), the two speed startup will be enabled. Thus, the dsPIC will start with the internal FRC clock and when the "user source clock" will be working, it will switch automatically to this source clock.



Is it right? (I did not tested yet the two speed startup ? )

Is this solution what you are asking for?



Lubin

Apologies! The "two-speed start-up" is a complete red herring: I misunderstood what it meant.

This simplifies things. If you give an option in the "Master" block which allows the oscillator

to be changed, that would help. I only want to set the oscillator once, as early as possible,

and I can do that with a block of my own, though it would be kind if you supplied one

yourself.

The reason why I need it is one which I don't fully understand (it depends on the

hardware outside the chip). For some reason, although our external oscillator is fine

(we start up with it), we can't start using the oscillator AND the PLL until later.

At the beginning of main() is not too early! Moreover, we do need to wait until the new

oscillator state is stable before using it. I therefore start with the XT HS oscillator, then

drop briefly to the RFC oscillator, and return to the XT HS oscillator, this time with the PLL.

The easiest way to do this is, as I suggested, to replace the existing PLL and CLKDIV

setting.



Bernard.

Hi Bernard,



I did not looked at this problem yet. I'll do it shortly...