[design log] Neat 2x170W I2S in, I2C controlled, integrated DSP amp (TAS3251)

[KaffiMann]

1600 rubles for the TAS3251 board, 400 for each output LC filter, 370 for the STM32F042 module and there's a USB to I2S converter for up to 32bit/96khz using STM32F446RC for 750 rubles.

So 1600 + 800 (400 each, need two of these?) + 370 + 750 = about 50 euro + shipping and taxes?

There's also ADAU1701 and 1761 boards for purchase.

I cant understand a single thing, but nice to see all the bits in a sort of wire nest thingy. :-)
YouTube

Almost like what it looks like at home

[JMF11]

Originally Posted by drMordor

RDC2-0050, Усилитель мощности класса D с цифровым входом I2S, 175Вт Stereo, TAS3251 | купить в розницу и оптом Amp
RDC2-0032, Управляющий элемент для проектов цифровой обработки звука. STM32F042 | купить в розницу и оптом Main load controller

Interesting links. It's good to see this chip gaining some attractivity. Even if it looks stange to associate it with another DSP, as there is a DSP already included.


Cheers,


JMF

[JMF11]

Small Functional analysis about should do the uC.

A board could be a Master or a Slave board.

On a slave board, the board uC manages:
- board Power ON sequence: /RESET_AMP after sufficient delay after power reached a sufficient level,
- board Voltage monitoring: /RESET_AMP in case of insufficient voltage (about 20V for ex),
- board FAULT management: /RESET_AMP after FAULT
- Power OFF sequence: /MUTE and /RESET from a GPIO state,

- To Be Confirmed: Jumper for RESET


On a Master board, the board uC manages:
- Slave functions for the local board
- DSP registers programming of local board and slave boards,
- Volume management via board pot and update of volume registers with I2C for local board and slave boards,
- Software Mute function (via I2C).


For complex projects, the uC should expose:
- 2 x I2C. As the TAS3251 can only have 2 I2C addresses, having 2 I2C is a solution to control 4 boards (3 or 4 way speakers)
- 3 x I2C could be interesting in very specific cases to cope with above cases and have the possibility to have a I2C master (RPi for ex) send volume controls to the uC to be relayed to the TAS3251,

- additional GPIO on a header.


This would allow a large panel of architectures. For ex:
- standalone stereo system (one master)

- standalone 2 ways active speakers (one master and one slave)
- RPi or Nucleo controlling 1 or 2 Slave boards
- ...


Any other features achievable with a stm32F0 chip ?

[dzwer]

I've just received the Russian TPA3255 bundle:
- amp: RDC2-0034a, Усилитель мощности класса D. TPA3255, PurePath, 315Вт Stereo или 600Вт Mono | купить в розницу и оптом
- output filters: LCF05, Выходной LC-фильтр второго порядка для усилителей мощности класса D | купить в розницу и оптом
- DC/DC convertor: RDC1-0013 15V, DC-DC преобразователь 60В / 15В, 1.3А, LM2575HV | купить в розницу и оптом
Forgot to buy the cooler: VC-D(S), Кулер для видеокарты , подшипник скольжения | купить в розницу и оптом
But I found one on an old PC mainboard Gigabyte
For PSu I use transformer and 10000uF cap and about 40V after the cap.
For now the P3A of Rod Elliot sounds better on the same PSU(+/-40V)...
I've bought the bundle to use it as evaluation board to test different output inductors and capacitors.
This bundle is around 50 euro with the shipping to Moscow, after that a friend of mine brought it to Bulgaria.

[AIM65]

You should be able to use the ADR line as a Chip Select :
On your UC connect a gpio out port to the ADR line of each TAS 3251 then connect together all SDA and SCL line. By software set all ADR line to 0. When the software wants to use a specific TAS3251, it set its ADR line to 1 and use I2c@ 4B, 96 and 97. Never use the @ associated with ADR =0.
Wtih this method you’ll be able to use an UC with a single I2C I/F wich will be probably cheaper and with smaller pin count. And you be able to drive as many TAS you want, for example for a 7.1 system…

[JMF11]

Originally Posted by AIM65

You should be able to use the ADR line as a Chip Select :
On your UC connect a gpio out port to the ADR line of each TAS 3251 then connect together all SDA and SCL line. By software set all ADR line to 0. When the software wants to use a specific TAS3251, it set its ADR line to 1 and use I2c@ 4B, 96 and 97. Never use the @ associated with ADR =0.
Wtih this method you’ll be able to use an UC with a single I2C I/F wich will be probably cheaper and with smaller pin count. And you be able to drive as many TAS you want, for example for a 7.1 system…

Thanks for the tip. Well noted. It looks like an elegant way to deal with the issue.


JMF

[topdevice]

Here is the firmware for the microcontroller STM32F042 which includes two TASS3251 at once. Github chipdipru

[JMF11]

So based on the above functional spec and advices, the board could have below connectors and Jumpers:



Basic conf:

• Connector: I2S (MCLK, SCLK, LRCK, SDIN, ???SDOUT)
• Connector: (I2C SDA, SCL, GND, ??3.3V)
• Pin Header: ADR, RESET_AMP, DAC_MUTE, FAULT, CLIP, GND
• Pin Header Fred Adjust
• Pin Header: Volume (+3.3V, AI, GND)
• Pin Header: ON/OFF (DI, GND)
• Pin Header for uC programming
• Jumper for ADR
• Jumper for RESET_AMP / Reset controlled by uC

Additions to be populated if needed:

• Connector: Oscillator Sync Interface (OSC-IOP, GND, OSC-IOM)
• Pin Header: additional I2S
• Pin Header: additional GPIO (GPIO1, ... GPIO5, GND)
• Pin Header: Aux Power 12V
• Pin Header: Auw Power 3.3V
• Connector "grouped I2S-I2C" for chaining boards (MCLK, SCLK, LRCK, SDIN, ???SDOUT, I2C SDA, SCL, GND, ??3.3V)

Does it makes sense ?


Any advice on standard, proven, (possibly cheap) connectors for the I2S and I2C connections ?


Is it possible to find Ribbon cable / coonectors trhat allow hobbyist to easily make connection cables between boards ? I would be happy to avoid having a mess breadboard type connections.


JMF

[AIM65]

You can use connectors for flat cable with 2.54mm pitch. It is easy to crimp them with a vice. 1.27 should be doable too.

https://fr.farnell.com/w/c/connecteu...very-surcharge

[Hrvoje Lasic]

Originally Posted by JMF11

You know, I don't do it for the money. If it had to pay just for my time, then it would cost much more than the limit you propose. There are very good alternatives like the hypex nCore or the 3e-audio offer. So it does not makes sense for to try to build a commercial product, with procurement, soldering, after sale.


However, it could be of interest for a Maker, with niche needs that would fit, interested with experimenting with the chip, but not with the TI EVM board :-)


For me, the learning is the reward (and it is still not the end of the road).



JMF

You could solder SMD components yourself. You need stencil (6 usd at jlpcb) and small oven that you can buy for 200-300 usd plus some thigns that you already have like magnifier, soldering iron etc.... I do it regularly for development purposes. It enables you to iterate quickly. You can also do small series.

for that you need to consider few things:
1) Keep passive components 0603 size or 0805 for bigger capacitor (i.e. 22u). 0603 you can hand solder if needed, anything less then 0603 it is difficult/impossible to manage. Also, it is easier to keep stock of passive components one size. 0603 you can hand solder/change if needed i.e. to tweak and quickly test.

2) Design one side only for SMD components. For TH components you can do as you like.
3) try to avoid small components i.e. for power supply, always look for alternative, it may be for example that one same component has several housings solutions. For diy SMD mounting, the bigger the better. you can do small ones as well, but not worth trouble if there is an alternative. Also, stencil needs to be clean for possible future use, small openings are more difficult to clean. You loose more time on cleaning usually then on actual soldering.



As for the price of the end solution without even looking BOM and what are you doing I am pretty sure you are not optimized. Passive components resistors, capacitors as said before keep 0603 size and forget, they are dirty cheap. Focus on all other components and check price in China. If component is not massively available in China try to find alternative, usually there is popular alternative that cost fraction of the price and is easy to get. If you correctly do this process you will be able to assemble PCBs i.e 20 pcs that cost same if you would assemble thousands in Europe, so you can be price competitive - this is how Chinese ppl do it (they are great entrepreneurs).


Regards,
Hrvoje