15in libre hardware laptop PCB progress
Luke Kenneth Casson Leighton <lkcl <at> lkcl.net>
2015-08-16 16:24:11 GMT
ok, so i started last week on the PCBs.
first thing: there's three of them. the casework, needing to have a
middle strut as well as other internal supports, makes it impossible
to have a single PCB, apart from anything that PCB would be just over
12in wide. also things need to be on different levels. so the PCBs
are divided as follows:
* PCB1 - contains the CPU card, I/O connectors, LVDS converter IC, USB
Audio IC, USB Hub, EOMA68 identifier EEPROM, and some ribbon
* PCB2 - contains an STM32F070 and 3 FPCs: one for the touchpanel LCD
(which has an SPI converter IC on it), one for the capacitive
touchpanel (I2C), and one 16+8 1mm pitch connector for the keyboard.
* PCB3 - contains the battery charger and power IC (an LTC4155) as
well as a battery monitor IC (STC3115) which measures current as well
as voltage. the LTC4155 is absolutely awesome, it has dual supply
inputs (5V in and USB-OTG), it can be turned round to *supply* 5V
USB-OTG, *and* it can provide up to 3A <at> 5V as system output.
all three PCBs will be double-sided 2 layer, with components only on
one side. cheap and cheerful. PCB3 will need to be 2oz copper
because it's dealing with 4 to 5 amps in places.
PCB1 is deliberately huge so that i have plenty of space to work with.
i have had to do a little bit of rearranging so that there are less
wires crossing over - for example, the MicroSD and the USB (CM108AH)
Headphone jack have now swapped places. as a result, the micro-sd