XO1.75 A2 A3 Changes: Difference between revisions

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These are the changes planned for the [[XO_1.75_B1|XO-1.75 B1 prototype]], from the [[XO_1.75_A2|A2 prototypes]].
These are the changes planned for the [[XO_1.75_A3|XO-1.75 A3 prototype]], from the [[XO_1.75_A2|A2 prototypes]].


=A2 Electrical Fixes=
=A2 Electrical Fixes=
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* Depopulate R335 and R345.
* Depopulate R335 and R345.
* Remove Q16, and short pins 2 and 3 (marked I and O).
* Remove Q16, and short pins 2 and 3 (marked I and O).
* Remove Q16, and short pins 2 and 3 (marked I and O).
* Remove Q21, and short pins 2 and 3 (marked I and O).


==VMEM stability==
==VMEM stability==
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The MISO and MOSI pins on J2 are swapped (the SOC GPIO map was wrong).
The MISO and MOSI pins on J2 are swapped (the SOC GPIO map was wrong).


SPI_MISO should be connected to U10.2, J2.1, and U11.AD15 (GPIO43)
*SPI_MISO should be connected to U10.2, J2.1, and U11.AD15 (GPIO43)
*SPI_MOSI should be connected to U10.5 , J2.4, and U11.AE15 (GPIO44)

SPI_MOSI should be connected to U10.5 , J2.4, and U11.AE15 (GPIO44)


=A2 Layout Fixes=
=A2 Layout Fixes=


- Bring GPIO04 (pin 5) to a user-probeable pad, for brick recovery purposes. (It may need to be grounded during EC flash reprogram.)
* Bring GPIO04 (pin 5) to a user-probeable pad, for brick recovery purposes. (It may need to be grounded during EC flash reprogram.)


=Planned Feature Changes=
=Planned Feature Changes=

Latest revision as of 05:46, 22 July 2011

These are the changes planned for the XO-1.75 A3 prototype, from the A2 prototypes.

A2 Electrical Fixes

These changes fix problems in the A2 prototypes:

SD power

These correct a mistake in Embedded Controller pin assignments for the SD power control signals.

  • Depopulate R335 and R345.
  • Remove Q16, and short pins 2 and 3 (marked I and O).
  • Remove Q21, and short pins 2 and 3 (marked I and O).

VMEM stability

This corrects an undercompensation of the +1.5V memory power supply, and also delays the turn-on of the memory termination power supply.

  • Change PR49 to 22K.
  • Change PR52 to 47K.
  • Populate PC37 with 0.1 uF.

eMMC

  • Populate R95 with 10K.
  • Connect BOOT_DEV_SEL to CN21.10
  • Use +3.3V_SD1 to power the eMMC instead of +3.3V_NAND

J2

The MISO and MOSI pins on J2 are swapped (the SOC GPIO map was wrong).

  • SPI_MISO should be connected to U10.2, J2.1, and U11.AD15 (GPIO43)
  • SPI_MOSI should be connected to U10.5 , J2.4, and U11.AE15 (GPIO44)

A2 Layout Fixes

  • Bring GPIO04 (pin 5) to a user-probeable pad, for brick recovery purposes. (It may need to be grounded during EC flash reprogram.)

Planned Feature Changes