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1079 discussions

Paypal sabotage crowdfunding
by Philip Hands 06 Dec '15

06 Dec '15

Hi Folks, Since this list has people that are reasonably likely to come up with crowdfunding projects, I thought I'd point at this sorry state of affairs, caused by Paypal: http://neo900.org/news/paypal-trouble-delays-project (the link to http://garethhayes.net/paypal-warning/ is hardly encouraging either) Cheers, Phil. -- |)| Philip Hands [+44 (0)20 8530 9560] HANDS.COM Ltd. |-| http://www.hands.com/ http://ftp.uk.debian.org/ |(| Hugo-Klemm-Strasse 34, 21075 Hamburg, GERMANY

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Free Soft & Hardware: ControLeo2 Reflow Oven
by Alexander Stephen Thomas Ross 04 Dec '15

04 Dec '15

came across this thought it might be on interest maybe. http://www.whizoo.com/

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15in laptop LCD up on PCB1
by Luke Kenneth Casson Leighton 04 Dec '15

04 Dec '15

http://rhombus-tech.net/community_ideas/laptop_15in/news/ it's by no means perfect, but i have at least data on-screen. i suspect EM interference is causing the corruption, so another revision of PCB1 will need the LVDS IC layout to be reworked. this is however huge progress. the only 2 parts of PCB1 that need to be checked and debugged are the MicroSD card slot and the 1W speaker/headphone amplifier circuits. the CM108AH USB Audio IC has already been confirmed as operational on the USB bus, as has the GL850G and the 3 USB ports. l.

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LTC4155 design flaw
by Luke Kenneth Casson Leighton 02 Dec '15

02 Dec '15

i've got an enquiry out with Linear, however it looks like there's a serious design flaw with the LTC4155 - not one that's safety-related but one that makes it functionally completely useless. the clue is in looking at page 15 of the datasheet - a diagram which shows the internal operation. in the bottom left corner is a power-selection arrangement, where there are two AND gates. note that they're not symmetrically arranged. the difference between the two is that WALLSNS output is connected to the *input* (inverted) of the USBGT enabler AND gate. what that means is that it is ABSOLUTELY CAST-IRON GUARANTEED - i.e. hard-wired in an inviolate way - that if the 5VDC input is plugged into a wall charger, USB OTG Host Power is ABSOLUTELY 100% WITHOUT FAIL ABSOLUTE guaranteed to be terminated without warning. which: (a) violates the USB-OTG Power Specification (b) is in direct contravention of the statement on page 1 of the LTC4155 datasheet which *clearly* states that the LTC4155 is compliant with USB-OTG Host Power Mode (c) is in clear violation of various laws like "Trade Descriptions Act" of the UK due to the qualifier statement in paragraph 2 which reads "....without needing additional components". all of which is a frickin nuisance, as i now have to go find alternative dual-supply OTG-compliant [boost-mode] battery charger ICs. i've found two already - bq24192i ($7 in low volume and it would require a 2A 5V step-up converter IC as well....], or the MAX77818 which is a 0.4mm pitch BGA - perfect because it even has battery status monitoring built-in, but the 0.4mm pitch BGA _wow_ that's gonna be tough for small china pcb assembly factories to deal with when they're used to QFNs and QFPs. argh! i'll let people know how this goes: i'm expecting to hear from Linear, they *might* confirm that the I2C "REQUEST_OTG" mode does in fact honour the USB OTG Host Power mode properly. if they do, then all is well - otherwise i will need to do a redesign of PCB3. l.

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qualcom snapdragon 410
by Luke Kenneth Casson Leighton 28 Nov '15

28 Nov '15

> [*] https://developer.qualcomm.com/hardware/dragonboard-410c > > ("Free graphics possible" according to the Debian Wiki's ARM 64 port page... > > https://wiki.debian.org/Arm64Port Adreno GPU. niiiice. minimalist hardware datasheet (with pinouts but not mechanical layout) on arrow electronics, as well as a five THOUSAND page datasheet on the hardware registers. this might actually qualify as an FSF-Endorseable processor, and, with a bit of work, might actually be a great candidate for an EOMA68 CPU Card. it will need a MIPI-to-RGB/TTL converter IC on-board. there's I2C, UART, SPI, 2 SDCs (one is eMMC, the other is SD/MMC), only one USB port (bleeeergh!), which means that a USB Hub IC is needed.. so we're looking at... whatever the SoC cost is (knowing qualcomm they'll want around the $12 mark for it), plus USB Hub IC and components ($1.50), plus a MIPI-to-RGB/TTL converter IC (could be as high as $2.50), so we'd be looking at what.... $15.... ... and the allwinner A64 we know is only $5. with 2 USB interfaces, RGB/TTL output.... whyy, god, whyyyyy... :) l.

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laptop power board
by Luke Kenneth Casson Leighton 28 Nov '15

28 Nov '15

.... i have the LTC 4155 15W power IC as well as the STC3115 battery monitor ICs recognised on the I2C bus with 5V power applied, yippeee. embarrassingly, i had the 5V DC socket wired reverse-polarity. this is, uhh, an officially-sanctioned test of the reverse-voltage protection on the power board design. no, really :) on a 2nd (minimally-populated) board i have the 5V regulated output up, but not on the fully-populated board. what i'll do is fill in all the components from the minimally-populated board, testing it as i go along. i'm looking forward to _not_ setting fire to the apartment when i plug in the e-bike lithium battery. unlike many of these "laptop" batteries it has no current protection circuit built-in, and it's perfectly capable of delivering 20 amps maximum current :) l.

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The $5 Raspberry Pi Zero is out
by joem 27 Nov '15

27 Nov '15

The $5 Raspberry Pi is out https://www.raspberrypi.org/blog/raspberry-pi-zero/ All sold out everywhere in hours :(

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laptop main board, power board and ingenic jz4775 cpu card
by Luke Kenneth Casson Leighton 26 Nov '15

26 Nov '15

ok, been quite busy, 3 to 4 different things going on. first one: i've been working on getting the eoma68-a20 board up and running (booting) out of NAND flash, that's been quite hair-raising. using a sunxi 3.15-10-rc5 kernel i was able to use the standard mtd-tools package to erase and write to the hynix TSOP48 NAND chip, placing an SPL-enabled recent version of u-boot onto it. this all worked fine... except it turns out that MLC NAND can self-destruct just by reading! all i can say is, no wonder allwinner's bootloader process is so damn complex! it's like a 4-stage boot: boot0 (minimum bring-up), boot1 (capable of reading NAND as well as SD/MMC FAT partitions), then u-boot (modified to read allwinner's strange partition format) and finally linux kernel. second, the jz4775 CPU Card is finally underway: http://rhombus-tech.net/ingenic/jz4775/news/ this is the first FSF-Endorseable CPU Card, using the 1.2ghz low-power Ingenic MIPS. it seems strange to put a $3 processor alongside $2.50 of NAND Flash and then put in almost $12 of DDR3 RAM ICs (2 GB RAM) but the threshold where SoCs were no longer the most expensive part of a BOM was passed a loong time ago. third, the laptop main board, i've got everything working except the LCD. i've blown up 2 LCDs already, it was necessary to buy 2 more. first mistake was that it was hard to read the datasheet so the connector was reversed: that resulted in -20V being shoved up the backside of the +3.3v sensitive ICs on the LCD, end result when i was finally able to make up a reversed-cable, the "magic smoke" left that LCD. also i hadn't noticed that i'd shorted the 5V rail to the 3.3v rail, which didn't help, and may have damaged some of the GPIOs on one of the EOMA68-A20 boards i have here. still quite a bit to investigate there. fourth, i've managed to smoke about 3-4 Power ICs already - various MOSFETs, two 3 Amp RT8288 PMICs from microdesktop boards i'm using for test purposes - all to get the laptop power / charger board up and running. annoying! but finally a couple of hours ago, by making up a 2nd board with minimal components, i managed to get the LTC4155 up and recognised on the I2C bus, as well as check that it was outputting stable 5V from USB-style input. the next phase is to populate the over-voltage and reverse-voltage protection components. it's getting there... it's just slower than i would like. l.

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laptop power PCB working!
by Luke Kenneth Casson Leighton 26 Nov '15

26 Nov '15

yaaaaa, i have battery-operation, i am currently running an eoma68-a20 off of a 10Ah e-bike battery, and both the LTC4155 charger/dual-supply IC and the ST3115 battery guage IC are up and recogniseable on the I2C bus. i have yet to compile up the linux kernel modules for both these devices, but they are both available... somewhere :) only slight issue to track down: power drops to 4V when the 5V DC is plugged in, i still have to investigate that, but it may be related to the setting of 3A input and i only have a 2A 5V charger. i can change the settings, and i can also "ping" the LTC4155 over the I2C bus... maybe :) but.... progress, yay! l.

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Cool Recycled Laptop Bag for EOMA-68 Laptop?
by Alexander Stephen Thomas Ross 23 Nov '15

23 Nov '15

http://www.protecttheplanet.co.uk/terracycle/denim-messenger-bag.html i look the look of it. made from scrap denim. I’d say looks the part for a laptop bag to sell/go with a eoma-* laptop. I wonder how the sew the scraps together? machine or cheap/slave labour?

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