Power Shield for Astroberry

picciux wrote: ATM 4 GPIO left unused. If GPS reset is not used and 3Dfix led can be sacrificed, we could have 6 gpios to let the unit control focuser stepper motors using already available Radeck Astroberry Focuser indi driver. On the power shield side, only a JST like connector to link one of those mini stepper controller modules is needed.

Yes, I am thinking about how to implement it, I do not really want to have the housing bigger, and currently, the front and back plates are full of connectors, based on my testing during the last week, it seems that I have to remove the onboard BME280, because the RPi temperature is influencing it quite much, so if I do so I would have space for another connector.
Do you think a JST 2,54mm pitch connector would be okay for that? I think an RJ11/12 is more common, or?

MCP3202 can be replaced with 3208 and populating 1 INA328 and OP-AMP per channel we'll have amps readings per-device instead of total. Maybe it's an overkill, don't know.

When I have started that design I have also thought about single-channel current measurement, and I am open to modifying it, with a smart MOSFET so I can also remove the fuses because the smart MOSFETs are overcurrent protected. This could help the place a stepper driver on the board.

the OneWire pin can be used to chain one or two DS18B20 temperature sensors to monitor stuff that has to be kept dew-free: since ambient temperature and relative humidity are already available, we can calculate dew point temperature and automatically regulate heaters at minimum power needed to keep dew away. Obviously lacking (or not working) the sensor, the channel works in manual power mode. I've already done it with Arduino, code is simple and I can contribute it.

As I mentioned previously the onboard BME280 cannot be isolated 100% from the RPi, so I am planning to remove it, and maybe add two 3,5mm jack connectors, one for I2C sensors, like BME280, and one for one-wire sensors. Let's see how all these fits on the board.

Hi Magnus,

mlarsson wrote: i.ebayimg.com/images/g/ItUAAOSw55FcVvQ9/s-l1600.jpg

Exactly, that is what I have also found in the catalog.
I will order a couple of, to study them.


Tibor

When I built my dew heater control box quite a few years ago I used DS18B20 on each strap to allow me to feed back and control the PWM to teh strap itself. This needed something different to the phono style connectors so I used 4 pin DIN connectors at the time.

I am really interested in this project - I think I would use off-board connectors to allow the above implementation plus that would allow for better weather proofed solution (though not watertight, but if I can avoid condensation getting in to the enclosure that would be good.

Looking forward to see how it progresses... and where I can help if possible.

I would worry if it tries to emulate the PPB Advance to a tee.

The moonlite focuser interface, for example, is something that I was hopeful to not have - no use for me, can be done via the Pi.

I guess the price point would be the key, whether this is better than a PPB Advance, tied with an Argon One M.2 case... or can take on the PPB Advance, with Pi4 integrated, with a type of Argon One M.2 thepihut.com/products/argon-one-m-2-raspberry-pi-4-case

Let's see where it goes...

gilesco wrote: I would worry if it tries to emulate the PPB Advance to a tee.

I do not really understand what you mean when you say "worry". This board is a HAT or Shield for Raspberry, without it, it is not able to operate. PPB is let say a stand-alone product.

The moonlite focuser interface, for example, is something that I was hopeful to not have - no use for me, can be done via the Pi.

Regarding the focuser, the target (basically the recommendation was) is to have a stepper output, means the currently existing Astroberry focuser Indi driver would be possible to use with this board.
So I am working on integrating a DRV8834 driver on board.

I guess the price point would be the key

I am also working on to get a price for machine populated boards.

tied with an Argon One M.2 case... or can take on the PPB Advance, with Pi4 integrated, with a type of Argon One M.2 thepihut.com/products/argon-one-m-2-raspberry-pi-4-case

The current mechanical design is based on to use standard aluminum extruded housings, this Argon One type would require a complete redesign, and the pre-cuted connectors (HDMI, USB-C ...) are useless for that design.

Hello,

AstroEQ uses the DRV8834 driver in Tom Carpenter’s device. I am using it now to operate my scope. Most of my time with it requires power to move motors. The potentiometer needs a VOM to set the amps. My NEMA 17 motors are cool to the touch when the amps are < 2.0 rating,

On Tom’s AstroEQ, the particulars data needed are number of teeth of the RA and DEC scope, the gear ratio of the motors, and any ST4 drivers. The software calculates the default slew rate.

tikiss wrote: Yes, I am thinking about how to implement it, I do not really want to have the housing bigger, and currently, the front and back plates are full of connectors, based on my testing during the last week, it seems that I have to remove the onboard BME280, because the RPi temperature is influencing it quite much, so if I do so I would have space for another connector.
Do you think a JST 2,54mm pitch connector would be okay for that? I think an RJ11/12 is more common, or?

I totally agree to keep the housing dimensions as they are. If you're talking about motor connector, RJ11/12 definitely is the way to go. I was thinking of a JST connector to optionally connect the motor driver module, but if you're planning to integrate it and provide directly a motor connector it's better.

tikiss wrote: When I have started that design I have also thought about single-channel current measurement, and I am open to modifying it, with a smart MOSFET so I can also remove the fuses because the smart MOSFETs are overcurrent protected. This could help the place a stepper driver on the board.

Overcurrent protected smart MOSFETs would be perfect, provided we have enough pin to interface them.

tikiss wrote: As I mentioned previously the onboard BME280 cannot be isolated 100% from the RPi, so I am planning to remove it, and maybe add two 3,5mm jack connectors, one for I2C sensors, like BME280, and one for one-wire sensors. Let's see how all these fits on the board.

I don't like 3,5mm jack connectors, seems to me they are not reliable and time-resistant; but it's only me and lacking a better alternative they're ok.

tikiss wrote: Regarding the focuser, the target (basically the recommendation was) is to have a stepper output, means the currently existing Astroberry focuser Indi driver would be possible to use with this board.
So I am working on integrating a DRV8834 driver on board.

Maybe I'm wrong but DRV8834 wants max 10.8V as motor voltage. Since we'll work in 10.5V-13.8V range, maybe it's better the A4988?