Sunday, October 31, 2010

GA330 guts

It's been some time now since I received the two Gemei A330 sent by ChinaChip (GA330 from now on, to distinguish it from the other A330 out there which is basically an A320 with 64MB RAM). We're still working out the details (NDA, possible trip to China) to acquire the required info on the CC1800 SoC (system-on-chip) in order to port dingux to it, and it might still take a bit longer. Please excuse me if I don't comment more on the matter until everything is settled.

I'm working on the x760+ dingux port. As I said, I have all the required info, but time is limited and I've invested most of it reviewing all my initial work together with recent developments. Please be patient (yes, even more, sorry).

Meanwhile, here you have some electronics pron:

You'll notice that there is no battery in the pictures. The samples were sent without battery due to customs regulations, and though it's not strictly necessary for development, I'll get hold of substitutes soon.

You know I don't use the A320 and GA330 much for gaming (lack of time, you know, bla bla bla), so I can't give you a thorough review of the new GA330. Here are some first impressions. Please bear in mind that I'm not sure to which point the samples I got are definitve production machines, so take it with a pinch of salt:
  • The construction build feels good but not as good as the A320.
  • The LCD is exposed, i.e. there is no plastic protection (which is part of the enclosure) over it, as happens in the A320 and the X760+. This is definitely a no-no.
  • The LCD is a "delta matrix" type. Don't know much about the technology (I'll appreciate links), but it basically means that the color dots are not aligned in an orthogonal matrix but spread in a zig-zag pattern. This is supposed to be better for displaying pictures and video, but I think it's not good for games.
Please let me stress what I already said: these might not be definitive production units and the final product to market may have many of these thingies fixed. Also, note that ChinaChip actively supporting linux on their machines is a huge advance, and a first in the chinese PMP market as far as I know. And more powerful machines will come in the near future.

One final comment on the CC1800: it as a video processing unit (VPU) capable of doing scaling and all kinds of color conversion. The JZ4732 in the A320 has an image processing unit (IPU) which unfortunately is only good for converting YUV to RGB. This is very useful for video playing but useless for gaming. The CC1800's VPU will allow to provide each game with the framebuffer resolution and color space which is best suited, allowing for a significant increase in performance. Being an ARM processor will allow also to use the already existing assembly optimized emulation cores, for another boost in performance.

Sunday, October 10, 2010

GPIO tables updated

ChinaChip provided the A320 schematic, so after studying it I've completed the A320 GPIO table here:

Some interesting updates:
  • PD3 and PD4 are unused GPIO but connected to test pads. Could be used for hardware mods (but first those pads would have to be located on the PCB). I'll open one of the A320 this evening and have a look.
  • PD22 is connected to the HOLD key (0=pressed, already pointed out in the comments by BouKiCHi).
  • PB30 confirmed to be battery charge status input.
  • PD20 is the battery charge control output (1=charge enabled). Actually, this turns on a NMOS which shunts a resistor to ground. This resistor is used to set the charge control, so in theory a PWM output could be used to achieve lower charge current. However, this pin's alternate function is SSI data output, so PWM might be achieved by spitting out continuously the appropriate data.
Not related to GPIO, but also interesting:
  • The FM chip audio output is (as expected) connected to the LINE_IN inputs of the JZ4732.
  • As I had guessed, the LCD read signal is not connected, and thus it is not possible to identify the LCD type or synchronize the GRAM refresh to the VSYNC.
As I mentioned earlier, I also have the x760+ schematics and I'm making the GPIO tables, soon to be published.

Friday, October 1, 2010

A personal note

When I sat to write the previous post didn't initially intend to get into the personal side. However, I felt I sort of owed you some explanation on my sudden disappearance, and besides that, I thought that remembering and summarizing the last year of frantic work would help venting a bit. Now that I read it again I have the feeling that I may have painted a gloomy picture on my job status and short-term future, but that would be a bit untrue, and I don't want anyone to worry about it. So, just to clarify: I'm not worried. If things end up well here where I'm now, fine. If they don't, I'm pretty sure I'll be able to find a new job, and in such case I'd really want it to be in another country (so does my wife), so moving abroad is actually an appealing possibility (and to some extent and foreseeing where this country is heading for, I even feel I owe it to my two daughters). And even if it's not that easy to find another job, I have no debt and savings to live on in the meantime.