Looking for information to Pulse Modulate or Amplitude Modulate using the OSK pin (66). I have try modulating the OSK pin(66). I am not sure how to set up the rest of the register.
OSK or Output Shift Keying pin is a digital input (active high). When the OSK features are placed in either manual or automatic mode, this pin controls the OSK function. In manual mode, it toggles the multiplier between 0 (low) and the programmed amplitude scale factor (high). In automatic mode, a low sweeps the amplitude down to zero and a high sweeps the amplitude up to the amplitude scale factor.
I'd like to refer you at page 22 of the datasheet for more info in setting up the appropriate registers.
I am confused by your answer which I think is the same as the datasheet description of pin 66 (datasheet p10).
First of all, p40 of datasheet specifies manual mode as when 'OSK enable' is 1 and 'external OSK enable' is 0. Without your description above a natural interpretation would probably be that amplitude would be set by the amplitude scale factor and the external OSK pin has no effect. I certainly did not expect what you and p10 say above. There is no other explanation of this mode anywhere else in the datasheet.
P40 of datasheet specifies automatic mode as when 'OSK enable' is 1 and 'external OSK enable' is 1. Page 22 specifies that in this setting the output is forced to 0 when OSK pin is low and set to the amplitude scale factor value when OSK pin is high. This is the same as what you and p10 say for the manual mode, hence contradiction.
So I am totally confused aout the OSK operation.
If what you and p10 is the correct version then what does the amplitude sweep in automatic mode mean? what step? what rate?
Before, when it was my first time to use the OSK function in the evaluation board, I also had the same confusion with you. I read the datasheet many times about the OSK function, but I only cleared myself with the confusion when I set-up the evaluation board and explored most of the configurations about the OSK function.
There are three bits involved in setting up the modes of the OSK function (AD9914 and AD9915):
Function Name Function Control Eval Board GUI
OSK enable Register Addr: 0x00  OSK enable
External OSK enable Register Addr: 0x00  External OSK enable
OSK Pin 66 External OSK pin activate
The Amplitude Scaling Factor (ASF) is the value entered to control the amplitude of the output signal. This can be found on the Profile modes and DRG modes in the evaluation board. Take note: ASF values are ignored when OSK enable = 0 be it in Profile or DRG. Likewise, ASF values are latched when OSK enable = 1.
External OSK enable acts as a mask to the OSK/External OSK pin activate. So if it is set(1) then OSK/External OSK pin activate is enabled. Otherwise, it is ignored.
If OSK/External OSK pin activate = 1, The amplitude of the signal is equal to ASF. Otherwise, the amplitude is zero.
The table summarizes the behaviour of the OSK functionality
ASF Registers Enabled
Amplitude = ASF
Makes sense. To be honest this is what I had expected, just waiting for your confirmation. Basically what is said in page 10 about the OSK pin is complete rubbish, it is not only confusing but also wrong, without this everyone would have the same understanding as you just explained by reading the other parts about OSK.
I have one more question. For the external OSK pin function you only mentioned ASF for Profiles and DRG modes, what about AMP in Parallel data mode? does the external OSK operation has the same effect here?
The datasheet says that the OSK enable bit should be set when you want to use AMP in direct conversion mode. I tried it in the setup and it does behave as indicated. Just an added note, you must disable the profile mode when you want to use direct conversion.
Dear LouijieC and Quang,
I was wondering what settings are needed to get the OSK hardware block to operate in 'manual' mode?
I understand the 'automatic' mode, external OSK (pin66) will raise the amplitude in a CONTROLLED swept fashion, and lower to 0 also in a controlled swept fashion, which is the purpose of the OSK hardware block, shown in Fig 35.
By comparison, in 'manual' mode, the OSK hardware block, pin 66 will INSTANTLY change the amplitude to either 0, or the amplitude setting in a profile register pointed to by the profile pins.
Now, since it appears that the OSK enable bit, (0x00) gets shared with enabling anything needed to control the amplitude, as stated on P42, " To engage any digital amplitude adjust using DRG, profile, or direct mode...,or OSK pin, this bit must be set"
So, in pursuit of manual mode, I would speculate that there may be a data source priority, for example, if the DRG is making amplitude data, then it has higher priority than the OSK hardware block manual mode.(assuming (0x00)=0)
I don't have an eval board in front of me at the moment, but allow me to speculate that manual mode can be achieved by setting the enable bits for DRG (0x01)=0, Profile(0x01=0,Parallel data port(0x01)=0
So, with every other possible source of amplitude adjustment disabled, does the manual mode of the OSK hardware block finally kick in?(or is 'manual' mode not accessible and should be scrapped from datasheet?)
One final note, Even though the OSK hardware block in manual mode will be using the profile pins inputs,
I am suggesting that profile MODE be disabled, as profile mode I think would just route the amplitude data from the profile register, without involving the OSK hardware block.
Thanks for helping me solve this mystery of how to activate the 'manual' mode of the OSK hardware block.
From my own understanding and confirmed by Loujie's answers, all the various wordings with regards to OSK is a bit of a mess. It is lot simpler than it sounds.
Don't worry about the 'manual' and 'automatic' terminology. Basically:
When 'OSK enable' is 0 then the level is always full scale.
When 'OSK enable' is 1 and 'External OSK enable' is 0 then the external OSK pin is ignored and the output level is whatever set by the selcted level control register (which one depends on which mode is active and the mode priority).
When 'OSK Enable' is 1 and 'External OSK enable' is also 1 then the output level depends on the state of the External OSK pin. If this pin is 0 the output level is forced to 0, if this pin is 1 then the output is again whaever set by the relevant amplitude register.
There is NO controlled sweep despite what said on page 10.about pin 66. There is some sort of mistake here which confuses the whole matter. If you ignore what is said here and just look at what is said on page 22 then you will be ok.
Which amplitude register is the one used depends on what mode you select and the mode priority if you select more than one modes. So if you only select profile mode then the level will come from the profile mode ASF register. If you select Parallel data only then the level will come from the Parallel data AMP register. If you select DRG and amplitude ramping then the level will come from this. If you select DRG and frequency ramping then the level comes from the profile ASF if profile is also selected etc... etc... what I am not sure about is if you selct DRG frequency ramp only and disable all the other modes I don't know where the pahse and amplitude will come from ... Loujie please help here.
I jope this helps
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