Thread: Announcements related to Neo900
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wpwrak is offline wpwrak
2016-06-23 , 01:36
Posts: 79 | Thanked: 719 times | Joined on May 2014 @ Buenos Aires, Argentina
#23
Originally Posted by freemangordon View Post
Please consider evaluating if gpios on the io extender should have wake-up capability,
We did a quick evaluation of interrupts, and is seems that most interrupts could end up in a wakeup role. The IO expanders we're interested in are all interrupt-capable (and can mask interrupts from lines that should not generate interrupts), so the CPU can simply wake-up on the interrupt from the GPIO expander.

I doubt this is correct, i2c1 should operate on 2.2MHz, at it is used to control twl4030 regulators (SmartReflex that is).
I2C#1 is not system-wide :-) Only I2C#2 and I2C#3 are. I2C#1 and I2C#4 only connect CPU and the companion chip but don't go to any other components. In any case, most IO expanders don't go above 400 kHz anyway. Only TCA6418 (1 MHz) and MCP23018 (3.4 MHz) are faster, but MCP23018 has only open-drain outputs, which would make it a somewhat inflexible choice. I'm also not sure if it is safe to share the SmartReflex bus with other components.

Also, IR diode on N900 is not driven by a simple gpio, but through PWM output. If TX diode on Neo900 is going to use the same, then it cannot be attached to iox.
Yes, CIR is a "fast" data signal, not one of the control signals mentioned in the white paper. In any case, in Neo900 we use the CIR mode of the UART (see IR white paper), which goes to a different pin (uart3_cts_rctx:H18 instead of gpt_9_pwm_evt:Y2; also, Y2 is likely to be occupied by HB USB).

In addition, twl4030 have 18 GPIOs, are all of them used?
Ah, good point, thanks ! There are indeed some we don't use (yet).

Thanks a lot for the feedback !

- Werner
 

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