Another processor with NRF52

RE: Another processor with NRF52

MartinBL — Tue, 30 Jan 2018 11:45:24 GMT

I would say that in general that is bad practice. There is a limit to how much current the nRF52's GPIOs can supply, and I suppose that the digital logic in the atmega can induce some noise back into the nRF52. I would rather suggest that you use some sort of mosfet to control the power supply to the atmega with a GPIO.

RE: Another processor with NRF52

Raja — Mon, 29 Jan 2018 15:44:33 GMT

So @endnode / @MartinBL i am planning to add a atmel processor to my custom board along with nRF52. I want to control when this processor is ON/OFF. Can i connect the vin for atmel (arduino based atmega328) to one one the digital pins on nrf52 and control its ON/OFF like we do for LED? Is it bad practice or we can do it like this.

Set pin: nrf_gpio_cfg_output(PIN_num);

Control ON by: nrf_gpio_pin_set(PIN_num);

Control OFF by: nrf_gpio_pin_clear(PIN_num);

RE: Another processor with NRF52

MartinBL — Thu, 04 Jan 2018 15:26:16 GMT

I'm glad you found them useful. Unfortunately this is all we have for audio: I2S example.

RE: Another processor with NRF52

Raja — Thu, 04 Jan 2018 14:04:34 GMT

Thanks @martinbl i also used your EasyDMA e.g. for mpu-9250 they were brilliant. Do you have any e.g. for audio also using nRF52?

RE: Another processor with NRF52

MartinBL — Thu, 04 Jan 2018 13:24:05 GMT

In addition to all the points @endnode has made I just want to point you towards some solutions and documentation. To do audio stuff you might be interested in the I2S feature of the nRF52. The I2S implements what we call EasyDMA that allows you to access internal Data RAM without CPU intervention. This in turn allows you to stream continuous data from RAM without worrying about the Softdevice. You can also use EasyDMA with the PDM to, to record audio, store it in RAM, and then stream it with I2S almost completely without CPU intervention (you will need software interrupts to update pointers to bufferes in RAM from time to time, but this can be done whenever the Softdivice isn't using the CPU).

Finally, here you can find some tables showing how much of the time the Softdevice uses the CPU in various scenarios: Bluetooth low energy processor usage patterns.

RE: Another processor with NRF52

endnode — Thu, 04 Jan 2018 11:16:15 GMT

Makes sense!

RE: Another processor with NRF52

Raja — Thu, 04 Jan 2018 09:21:52 GMT

Thanks @endnode your points are very valid. It is a great forum and nordic is doing good job also skilled people like you also contribute a lot and i respect it. I use to develop on Arduino at start then realised i need to properly develop using industry standard hardware and tools. So i moved to Nordic chips as i need BLE for what i need to develop. They have great forum here with tutorials. So in past 3 months i have learned a lot. Now i can comfortably develop BLE services talking to my custom made apps on iOS and android. I have learned how to integrate different hardware components. For some i am still finding ways like for touch screen display/audio out/microphone etc. Also i was able to use open source tools in my journey here. I have been developing software professionally for last 20 years and have moved a lot between different technologies like server side, web, desktop, databases, big data and mobile this was only possible as in software side companies like microsoft, oracle, google apple spend lot of time writing tutorials for new developers to there platform so i would request nordic to take same approach and carry on there amazing works by adding new tutorials every 2 weeks and keep there existing tutorials upto date.

RE: Another processor with NRF52

endnode — Wed, 03 Jan 2018 21:58:13 GMT

..like SDK examples, release notes etc. are written for people who already have a clue about embedded programming or at least want to take it seriously. If some artist or hobbyist or whoever have great idea but don't want to spend on his/her blinking-whatever more then 2 weeks then he/she should find professional and pay him for the job rather then complaining that embedded programming on nRF5x cannot be learned in one week. Again just my opinion.

RE: Another processor with NRF52

endnode — Wed, 03 Jan 2018 21:55:43 GMT

And one more: I hope Nordic support team will appreciate your feedback on lack of tutorials (which I personally would argue a lot because you have TONS of tutorials and examples for nRF5x) but I believe you understand what's happening here: Nordic isn't non-profit organization which releases low-cost boards for DIY/hobbyists/teaching of kids (which Arduino more or less is), it's publicly listed private business which wants to sell as much chips as possible. Who is then main focus? Big OEMs and similar companies embedding low-power radio chips to all different electronic devices and pushing hundreds of thousands of them to the market every year. These guys have teams which don't work on Arduino IDE level, they are embedded SW and HW professionals. So you need to understand that while Nordic is so nice and kind to support everyone on this forum, the main focus of all the support materials

RE: Another processor with NRF52

endnode — Wed, 03 Jan 2018 21:48:07 GMT

My comment on that would be: Arduino and its IDE might be great for beginners but most of them will be locked in misconceptions learned there and they will never develop good working embedded FW. So my first recommendation to everyone is to avoid any shortcut because some things are simply complex and must be understood into the roots to design something meaningful. Better 6 months of learning of proper ANSI C coding and concepts then having fast blinking *** but never being able to do anything more complex. Similar comment to the "suggestions" that nRF5x with Nordic BLE stack has limitations: sure it has. However it impacts 1% of applications. All the rest are either perfectly doable (I've seen nRF52 app which was running SPI+I2S+I2C+PWM+BLE at the same time and it was perfectly stable) or impossible requirements from the start. But I'm biased so indeed this is just my opinion.

RE: Another processor with NRF52

Raja — Wed, 03 Jan 2018 16:47:26 GMT

Thanks @endnode. I agree it has enough power but lot of other posts say when softdevice is running then some scenarios will not run properly. e.g. Post. I feel as compared to other communities like ARM/Arduino NRF5 chip lacks greatly in tutorials and examples for non electronic background hobbyist. I hope this gap can be filled as NRF5 chip gets more and more popular.

RE: Another processor with NRF52

endnode — Wed, 03 Jan 2018 16:08:13 GMT

Well nRF52 has enough power and peripherals to run as single chip in most embedded systems. But it requires certain embedded SW and HW development skills to over come all challenges. You can indeed take opposite approach to just wire multiple of chips over SPI/I2C/UART and let each of them do more or less single function (sensor data gathering, radio communication, audio input, audio output...) In normal commercial product this would be probably unacceptable because of high BOM and manufacturing cost but for prototyping/small batch/hobbyists this approach is fine as well.

I won't advise you on what chips you can pair with nRF52 because basically everything what can do UART/SPI/I2C/I2S will work.