[TriEmbed] Chain-able EEPROM or Similar

[Adam Haile]

interesting idea. Though I'd like to avoid placing anything else inline
with the LEDs themselves. Mainly because of performance. Although maybe I
could use the same chip as what I need... just not sure how to *read *from
a chain like that. Only write....

On Mon, Nov 30, 2015 at 2:21 PM, Shane Trent <shanedtrent at gmail.com> wrote:

> Adam,
>
> You could use an 8-pin ATTiny to as your 0th element in each array and
> have the data in flow through but a command to the new 0th element would
> return your string length. Bit-bang to match your desired protocol and you
> are good to go. As a side note, here is a cool article where they measured
> the power supply drop to determine the number of addressable LEDs on a
> string. You would need a seperate data line for each string or to have ALL
> of the LEDs in series but it is food for thought.
>
> https://cpldcpu.wordpress.com/2014/11/16/ws2812_length/
>
> Shane
>
> On Mon, Nov 30, 2015 at 2:15 PM, Carl Nobile via TriEmbed <
> triembed at triembed.org> wrote:
>
>> Adam,
>>
>> The only thing I can think of that may work in your situation are 8 bit
>> latching shift registers. Here are two links to PDF datasheets that could
>> help.
>>
>> https://www.fairchildsemi.com/datasheets/MM/MM74HC595.pdf
>>
>> http://www.ti.com/lit/ds/symlink/sn74ls673.pdf
>>
>> ~Carl
>>
>> On Mon, Nov 30, 2015 at 2:08 PM, Adam Haile via TriEmbed <
>> triembed at triembed.org> wrote:
>>
>>> Oh... yeah. Important part. The data in the chip needs to be
>>> non-volatile!
>>> So, the data would be stored on each chip individually and then read
>>> serially.
>>>
>>> On Mon, Nov 30, 2015 at 2:07 PM, Brian <triembed at undecidedgames.net>
>>> wrote:
>>>
>>>> If you can spare three pins, shift registers are (maybe) exactly what
>>>> you need.
>>>>
>>>> You didn't mention how the bytes get there to begin with, which does
>>>> affect the answer.
>>>>
>>>> Most (?) serial-out shift registers support chaining out-of-the-box;
>>>> they have a latch signal to preload their internal flip-flops as well as an
>>>> external serial input.  By their very nature, the first (n) bits clocked
>>>> out will be their own bits, followed by whatever bits clock in on the
>>>> serial input.  Natural chaining.
>>>>
>>>> If you have parallel inputs that can all be latched at once, a single
>>>> latch + clock-out + data-in is all you need on the host MCU.
>>>>
>>>> If the data comes into the registers serially, well, that's a bit more
>>>> complicated.
>>>>
>>>> -B
>>>>
>>>>
>>>> On 11/30/2015 1:35 PM, Adam Haile via TriEmbed wrote:
>>>>
>>>>> I have /no/ idea if this technically is something that exists, but I
>>>>> have to imagine it's possible.
>>>>>
>>>>> I need a small, cheap (isn't it always?) chip that can store a few
>>>>> bytes
>>>>> of data. Actually a single byte is all I need. And can be accessed kind
>>>>> of like a shift register where I can query an unknown number of devices
>>>>> int the chain and get, in order, the byte that each one stores.
>>>>>
>>>>> The intent here is  so that I can have multiple, pre-wired, sets of
>>>>> LEDs
>>>>> with an arbitrary order and number of LEDs on each. This chip would
>>>>> store the LED count for each pre-wired section. Without knowing
>>>>> anything
>>>>> about the pre-wired sections, I need to be able to poll all these chips
>>>>> and from that know how many pre-wired sections there are, how many LEDs
>>>>> each has, and in what order. The data returned just needs to basically
>>>>> look like: 48, 36, 24, 18 (4 sections with 48, 36, 24, 18 LEDs, in that
>>>>> order).
>>>>>
>>>>> I assume it would use an SPI-like interface... not exactly since I
>>>>> can't
>>>>> use chip selects. Since I would have an arbitrary number. A 2 wire
>>>>> interface would be great. Is it possible to do something like this with
>>>>> I2C? Basically, I know what I need, but don't know what to call it.
>>>>>
>>>>> Any thoughts?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>> TriEmbed at triembed.org
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>>>>>
>>>>>
>>>>
>>>
>>> _______________________________________________
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>>>
>>
>>
>> --
>>
>> -------------------------------------------------------------------------------
>> Carl J. Nobile (Software Engineer)
>> carl.nobile at gmail.com
>>
>> -------------------------------------------------------------------------------
>>
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>>
>
>
> --
>
> A blog about some of my projects.  http://fettricks.blogspot.com/
>
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