[sdiy] SOIC audio ADCs & dsPIC33F devices with codec interfaces not shown as such in the selector chart
Scott Gravenhorst
music.maker at gte.net
Sat May 25 17:26:05 CEST 2013
Hi Robin and Tom,
For me, Microchip documentation has always been a bit weird. I remember going through
this exercise awhile back and made the determination at the time that dsPIC33FJ128GP802
(which is a 28 pin DIP part) did not have the DCI module. I can't remember how I came to
that conclusion, but today I looked at the ASM30 supplied file p33FJ128GP802.inc and it
clearly has references to the DCI module registers and register bits. Now I'm somewhat
befuddled again about this. I've got a project that I'd prefer to do with
dsPIC33FJ128GP802, but I need the DCI. Is there, in fact, a DCI module in this part?
I had never seen that part selector page before, it is indeed in error.
Tom Wiltshire <tom at electricdruid.net> 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
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at dropmix.xs4all.nl
>http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- FPGA MIDI Synth Info: jovianpyx.dyndns.org:8080/public/FPGA_synth/
-- FatMan Mods Etc.: jovianpyx.dyndns.org:8080/public/fatman/
-- Some Random Electronics Bits: jovianpyx.dyndns.org:8080/public/electronics/
-- When the going gets tough, the tough use the command line.
More information about the Synth-diy
mailing list