[sdiy] SOIC audio ADCs & dsPIC33F devices with codec interfaces not shown as such in the selector chart
Robin Whittle
rw at firstpr.com.au
Sat May 25 12:34:01 CEST 2013
Hi Tom,
The problem is that the selector chart and the individual web pages for
the devices state that these devices do not have a DCI interface, when
in fact they do. The datasheet is correct in stating that they do.
Someone told me recently that couldn't think without a cup of tea. That
was my experience too. My mornings and days in general are clearer and
more productive since I stopped using caffeine in 2004. I quite often
have good ideas lying in bed in the morning, or in the first hour or so
after getting up - putting things together in ways I had not thought of
the day before. There's something loose about the first hour or two.
Newspaper headlines are at first seen to mean something more bizarre
than they actually are. Fresh combinations of ideas about electronics,
molding epoxy composite dummy heads for binaural microphones, physics
etc. float into my brain. Not all of them survive later scrutiny.
You wrote:
> PS: MPLAB X isn't so bad once you get into it. I used it all winter.
> It still isn't finished yet , though. The worst flaw I found was that
> the simulator updates so infrequently as to be useless. I need to
> know *after each instruction* what the values of variables and memory
> locations are, and it only seems to update every four or five
> instructions or worse.
I gave up on MPLAB-X 1.70 on March 13th when it would not recognize
breakpoints:
http://www.microchip.com/forums/m698959.aspx
I also found there was no way of specifying a Watch for a program
variable by name.
Both these faults were completely prohibitive. So I went back to
ordinary MPLAB. The forum has many reports of unusability, such as:
http://www.microchip.com/forums/m725214.aspx
I haven't tried 1.80 which was released on May 7th.
- Robin
On 2013-05-25 7:41 PM, Tom Wiltshire wrote:
> Hi Robin,
>
> Sorry, I don't understand this email. You've confused me.
>
> I don't get what the problem is that you reported to Microchip. You mention having reported it, but not what it was.
> Then you say that the data sheets for a list of devices are erroneous, because they don't mention DCI. Except that some of them do. Are you saying that Microchip list it when it isn't there, or that they don't list it when it is? Or something else?
>
> I think maybe I need another cup of tea this morning. I'm not getting it.
>
> Thanks!
> Tom
>
> PS: MPLAB X isn't so bad once you get into it. I used it all winter. It still isn't finished yet , though. The worst flaw I found was that the simulator updates so infrequently as to be useless. I need to know *after each instruction* what the values of variables and memory locations are, and it only seems to update every four or five instructions or worse.
>
> On 25 May 2013, at 07:29, Robin Whittle <rw at firstpr.com.au> wrote:
>
>> For those unfamiliar with the dsPIC33F series, these microcontrollers
>> cost a few dollars and have a 40MIPS 16 bit CPU which can be used, with
>> care, to do a full multiply accumulate, with all fetching and storing,
>> pipelined so this occurs in a single instruction cycle.
>>
>> A particularly interesting aspect of these it that some have a good (so
>> I believe, it has been mentioned on this list - I haven't used it yet)
>> sigma-delta stereo audio DAC on board and that some of these devices are
>> in 28 pin DIP packages.
>>
>> They don't have matching audio ADCs - just conventional 12bit successive
>> approximation ADCs. This raises a question of how we can connect an
>> external audio ADC. This leads to the question of whether these devices
>> have a "Codec Interface" - a section which connects with a few wires and
>> the I2S protocol to an ADC, DAC or CODEC. This section does DMA to
>> circular RAM buffers and interrupts so it can be used without much CPU
>> intervention.
>>
>>
>> I reported this problem to Microchip in May 2010 but never got a reply.
>> The problem remains and I reported it to them at
>> webcorrections at microchip.com again today, requesting that they reply.
>>
>> The selector chart at:
>>
>> http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=8192&mid=14
>>
>> and the individual device webpages which are linked to from this are all
>> erroneous for the devices listed below, in that these devices DO HAVE a
>> "Codec Interface" AKA "Data Converter Interface" AKA DCI, which can be
>> used to connect to I2S interfaces on (typically) stereo audio
>> sigma-delta DACs, ADCs or Codecs (both DAC and ADC). This can be
>> verified by looking "DCI" in the include files for each device which are
>> part of the MPLAB (not MPLAB-X . . . which I and other people have found
>> difficult to use). This chart and the associated webpages indicate that
>> these chips DON'T have this interface.
>>
>> These devices are all covered by the one datasheet:
>>
>> http://ww1.microchip.com/downloads/en/DeviceDoc/70292G.pdf
>>
>> Here are the chips with a few pertinent details. This will only look
>> good with a fixed width font. The sizes for Program and Data RAM are
>> bytes, so divide by 2 to get 16 bit words. For most of the devices, 2k
>> words can be used by DMA.
>>
>> The DAC pins refers to the 16 bit sigma-delta stereo audio DAC which
>> some devices have. Both the 4 and 6 pin options are fine for stereo.
>>
>> Pins Prog Data DAC
>> dsPIC33FJ128GP804 44 QFN TQFP 128 16 6
>> dsPIC33FJ128GP802 28 SPDIP SOIC QFN-S 128 16 4
>>
>> dsPIC33FJ128GP204 44 QFN TQFP 128 8 -
>> dsPIC33FJ128GP202 28 SPDIP SOIC QFN-S 128 8 -
>>
>> dsPIC33FJ64GP804 44 QFN TQFP 64 16 6
>> dsPIC33FJ64GP802 28 SPDIP SOIC QFN-S 64 16 4
>>
>> dsPIC33FJ64GP204 44 QFN TQFP 64 8 -
>> dsPIC33FJ64GP202 28 SPDIP SOIC QFN-S 64 8 -
>>
>> dsPIC33FJ32GP304 44 QFN TQFP 32 4 -
>> dsPIC33FJ32GP302 28 SPDIP SOIC QFN-S 32 4 -
>>
>>
>> The 28 pin DIP devices are of particular interest since they can be used
>> without SMD heroics.
>>
>> There's no such thing, as far as I know, as an I2C ADC or CODEC which is
>> in a DIP package. SOIC is the only chip package which I think can be
>> hand-soldered without SMD heroics. There are a few such ADCs:
>>
>> TI (ex Burr Brown) PCM1801: 5V SOIC 14 pins
>> Wolfson WM8738: 3.3V SOIC 14 pins
>> Wolfson WM8783: 3.3V SOIC 8 pins
>>
>> The Wolfson devices are listed here:
>>
>> http://www.wolfsonmicro.com/products/adcs/
>>
>> and are available at Mouser and/or Farnell/element14. They are
>> inexpensive, such as, for the 8 pin WM8738, AUD$2.48 (Q 1 - 9) at
>> element14 (in stock) and at Mouser (not yet in stock) $1.12 (Q 100+)
>>
>> I find it easy to hand solder an 8 pin SOIC. I will be investigating
>> the WM8783 since the WM8738 has no obvious advantages over it. As far
>> as I can tell, it should be straightforward to interface the WM8783 with
>> the dsPIC33FJ128GP802.
>>
>> - Robin
>>
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