jimbostlawrence
- 16th August 2012, 09:42
Hi,
I've been playing around with micro SD cards for a few months now. One thing I've noticed now that I've had help getting the CPU to run at minimum speed and properly go to sleep (thanks guys!) is that, when in a sleep after having just written a single block to the SD card (writes periodically), there is still up to 7 mA being taken by the SD card - I know this as if I pop the SD card during this period, the current drops right down to under a mA (sensors/PIC taking the rest). The SD doc's say the SD card should go into idle mode and draw about 100 uA automatically upon completion of a command from 'the master' so surely it should have done this AFTER A FEW SECONDS!? The routines work fine and write single blocks sequentially to the SD card so as far as I can tell, so a bit perplexed. Is there something special with the lines you have to do to ensure it knows the 'master' has released it? Have the DI/DO,DAT1/2/!CS pulled high with 50k resistors...
Has anyone ever measured the current from an SD card inbetween block writes?
Cheers
Jimbo
I've been playing around with micro SD cards for a few months now. One thing I've noticed now that I've had help getting the CPU to run at minimum speed and properly go to sleep (thanks guys!) is that, when in a sleep after having just written a single block to the SD card (writes periodically), there is still up to 7 mA being taken by the SD card - I know this as if I pop the SD card during this period, the current drops right down to under a mA (sensors/PIC taking the rest). The SD doc's say the SD card should go into idle mode and draw about 100 uA automatically upon completion of a command from 'the master' so surely it should have done this AFTER A FEW SECONDS!? The routines work fine and write single blocks sequentially to the SD card so as far as I can tell, so a bit perplexed. Is there something special with the lines you have to do to ensure it knows the 'master' has released it? Have the DI/DO,DAT1/2/!CS pulled high with 50k resistors...
Has anyone ever measured the current from an SD card inbetween block writes?
Cheers
Jimbo