08-18-2018, 01:12 PM
(08-16-2018, 02:56 AM)lucho Wrote: OK, so the question is not whether this is needed but only who could write it. I couldn't write a whole manual, but could at least add some information to the wiki page. For example, one of the most important (albeit small as it may seem) omissions is the role of the SW4 jumper. Here's what I've written elsewhere in this forum (slightly edited):
The possible combinations are summarised below (1 = present, 0 = not present, S = boot from the microSD card, M = boot from the eMMC module, X = unsupported combination):
Code:microSD eMMC SW4 boot
0 0 0 X
0 0 1 X
0 1 0 M
0 1 1 X
1 0 0 S
1 0 1 S
1 1 0 X
1 1 1 S
Is this table correct? (I must be 100% sure before I add it.) If so, where on the wiki page is best to add it? The "Storage" section? It could also be helpful to explain how to remove the jumper "on the fly" several seconds after turning the power on in order to boot from the microSD card but then obtain access to the eMMC card. (This trick has been discussed elsewhere on this forum.)
I think its close enough. In the noobs it states:
There is an unlabelled (on the PCB silk-screen) 2-pin jumper (15) between the eMMC socket (13) and the SPI chip (16). The default condition is OPEN (no jumper). It is useful for controlling the boot as follows:
Default boot device (with no SPI software) is eMMC, then SDcard. If both the eMMC and the SDcard contain bootable images then the eMMC can be disabled by installing the jumper. This completely removes the eMMC from the resulting OS. If you wish the eMMC to be visible in the booted OS the jumper should be removed 2 seconds after applying power (and before the white LED comes on).