SDI Technologies SDIO Card Benutzerhandbuch

 

 

 

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 46 

•  The host shall have the ability to manage power by calculating maximum current shown in the tuples 

and control EMPC, EPS and IOEx not to exceed total current that the host can supply. If the host does 
not have enough power to use the card, the host shall not enable the card. 

 

 
A host reads the SMPC to see if the card supports Power Control additions. If so, the host checks SPS to see the 
card’s support of Power Selection. If SMPC is set to 1, a version 1.10 host should set EMPC to 1. 
Power Selection provides the host with the choice of two power modes for the function. A host that can supply 
enough power to the card does not need to use Power Selection. 
 
If SMPC is set to 1 and SPS is set to 1, the host can utilize Power Selection by setting EMPC to 1. If EPS is set 
to 0 (default mode of the card), Higher Current Mode is selected. If EPS is set to 1, Lower Current Mode is 
selected. For example, a wireless function may offer a power mode with reduced transmission range and 
corresponding reduced current requirements. As the host knows how much current it can supply to the card, it 
reads the appropriate tuples and decides whether or not to enable each function (with IOEX), and if so in what 
Current Mode. The host shall verify that the total current required by the card shall not exceed the current of host 
can supply.  A version 1.10 host should read new tuples as shown in Table 11-1.