BasicPI

Ethernet Ground Plane

Posted on by Jan

Just showing the ground plane on the Ethernet/Wifi Hat. I am very pleased with this one and the approach I used here. Earlier as I routed I have routed on both sides with ground plane becoming very fragmented. On this one I only used ground plane as an exception and only for minimum distances. The cost is that I go forth an back a little, but the result was a much better ground plane with no fragmentation of areas.

I feared routing Ethernet would be difficult an result in a very fragmented board, but it has actually gone much smoother than expected and with a very good ground plane as result.

I do however keep promissing myself to move to 4 or 6 layer PCB’s once I have the prototypes working. I don’t need extra layers for routing, I need extra layers for EMC and noise reductions as I start penetrating higher frequency signals. But, well – if this works on 10Mbps and not on 100Mbps we know the reason and how to fix it. I will annotate the new Hat later.

Modular Control System

Posted on by Jan

This drawing is an overview of the Hat’s in progress. A few is only on the planning stage, but most electronics is on prototype level and SW is coming on.

Raspberry PI is the obvious core if I need heavier processing. Due to the nature of it’s SPI I can only connect one of these on the same bus. But, it is not given that the bus here must be SPI as we also can dig into Ethernet, Wifi, Serials, CAN, LoRa and NB-IoT.

Wifi/Ethernet Switch is new. I am thinking of HLK-7688, but I need a switch regardless to use Ethernet and Wifi in a system. I will do some experiments this authumn to see if I can achieve something here.

Ethernet/Wifi Hat is on it’s way. This is a simple replacement of Raspberry PI that allows me to add multiple Ethernet/Wifi connection points. Excellent for secondary connections or low cost adaptors. Or well – low cost – the price of a Raspberry PI is hard to beat due to it’s high volume production, so lets see.

LoRa/GPS is on it’s way. I have the first PCB (with errors), but I have not found the time to assemble them yet. I actually considering updating the PCB before I crack on. I am a bit eager to learn more about this technology as it provides free radio up to 12ich km in line of sight.

NB-IoT Hat has same status as LoRa – I have the PCB, but lack subscription and time. I actually need a SIM card w/subscription to connect to the telecom network for this – again a technology I would like to learn more about. If my understanding here is correct I can connect from isolated places to monitor data with this.

XPortHub is made, but I need a revision + I also consider making a variant with Pro-EP10 or similar to get a Ethernet connector. The SW on this is also coming on as this is the project I use to build infrastructure. The plan is to duplicate AL/tools on all Hat’s and start adaptions later this year.

Sensor Hat is on it’s way. This is a Hat offering connections to multiple sensors Analogue, Digital, SPI and I2C.

3D sensor is only on draft level. I have components and need to find time to experiment. This will include GPS, Magnetometer, Gyroscope, Accelerometer, Pressure (Altitude), Temperature and humidity. The target is 3D sensors for motion drones.

Watchdog is new on this list. The idea is a separate Hat that monitor/power on/off the rest.

PSU is 5V PSU feed from higher voltage + maybe I make the watchdog capacity here. Watchdog and PSU are ideas, but not very mature ones – that said it is obvious that I need to find a battery/PSU solution for my systems.

32xServo/IO Hat – I have an older version of this, but have not ordered the new PCB. I need to do a review with focus on the Servo part with some testing. Some pins can be driven by timers, but I do not have 32 PWM channels, meaning that some pins will need software feeding or be IO only. It might be that this is reduced to 16xServo +16xIO etc. To be honest 16 servo ports are rather high density + I can stack these boards up. I also have an issue with these right angle header connectors so it could be an idea with proper connectors that do not fall off etc – I have to look into options.

8xDC + 16xIO Hat is not ordered. Again I have old versions that I want to experiment with first. This Hat might actually be ditched because the 12xPWM can drive 6xDC + I have a ESP32 project that also can drive multiple DC motors if I need more optional space.

12xPWM Hat is on it’s way now. This is maybe the most powerfully motor Hat I have as it can drive 12xSolenoids, 12xPWM signals, 6xDC Motors, 4×3-phase motors or 3xSteppers with current sensors.

3KW Universal Motor Hat. My 160 component steam-punk monster. My wife named this Steam-Punk Driver due to the thick cobber wires. I have to admit that I have assembled, switched on PSU power that works fine and hidden it for a boring day The driver is so powerfully that I lack a project/usage for it. But, the 3KW Thunderstick targeting 3-Phase motors is on it’s way + I am waiting for a new motor. I actually have a 3KW motor, but I need mounting for it + hrmfff PSU to test. The 3KW UniMotor will be completed because I like that project, but I fear I lack project for it.

7x5Wire Stepper is assembled and tested. Motor code is ready, but it needs a new PCB with minor fixes and AL infrastructure so it can go into a system. This is dedicated the small 5-wire steppers that cost ca 1.- USD.

LAN8710 vs Pro-EP10

Posted on by Jan

Again I am not done routing, but I wanted to illustrate ca the space cost of adding an Ethernet Phy and why I was so interested in Pro-EP10. You can see Pro-EP10 footprint at left in green, while LAN8710 and RJ45 w/magnets build in is in blue at left. Using Pro-EP10 would be a huge space saving + the Linux means you can have things like Web servers on separate processors – which we also can since we have ESP32 for this purpose.

The drawbacks with Pro-EP10 is cost (ca 18.- USD), reduced bandwidth through a serial Interface and more complicated toolchain on an embedded Linux. The later is not really that limiting because the MCU’s we use will struggle with higher bandwidth, so it will work out. I already have a Pro-E10 and it will cost me a bit of time and ca 20.- USD to do a demo Hat, so lets see. I am actually considering adding Pro-EP10 to XPortHub.

That said HLK-7688 is much better beacause it offers Wifi and 5 Ethernet ports with a 150Mbps bandwidth switch build in – assuming I can use the SPI as I want and get control over the toolchain. The later is the main drawback with these Linux options. ESP32 on the other hand is well supported and have an excellent, easy to use Toolchain.

Wifi/Ethernet Hat

Posted on by Jan

Not routed the Hat yet, but got all components on the PCB and it looks possible. Using an optional 2.4Ghz antenna on this one. It will take ca 1 week and I probably have the first draft routed. It tends to og fast once I start. What I usually do is to do a bit now and then and suddenly it’s done. I have mentioned this before that I find PCB Routing like a relaxing mind-game.

Wifi/Ethernet Hat Drafts

Posted on by Jan

Getting on with my ESP32 based Wifi/Ethernet Hat. First draft of schematics below. This is the first time I try LAN8710 so all bets off. I am most worried about the 100Mhz signals here. The next picture show components before I place and route the PCB. This looks tight tbh.

LANEnable will switch power on/off enabling me to run with only Wifi or only Ethernet. The rest is IO for Ethernet RMII Interface. I have ordered some breadboards to Experiment With this before I see any point ordering it.

Ethernet Hat’s ESP32/HLK-7688A

Posted on by Jan

I decided that I want to make 2 different Ethernet/Wifi modules With different purpose. With Raspberry PI it will be 3, but RPI and ESP32 overlap in functionality.

ESP32 with Ethernet/Wifi/Bluetooth is a very attractive “Connector” solution where I can add more connections by adding multiple Hat’s. I can sadly only add a single Raspberry PI since it only support Half Duplex Master on the SPI. 

HLK-7688A is attractive because it is a switch/router. I can probably do this with Raspberry PI as well, but with HLK-7688A it was straight forward to connect with the OpenWRT package. I am not so sure with interconnection to the backbone, but that is work to do. I have to admit that I am still a bit undecided on HLK-7688A because support and information is not that great, but we will see. And even if Raspberry PI can be used as a Switch/Router it still have to deal With the Ethernet/Wifi IO bandwidth. It maked perfectly sense to offload this to a HLK7688A based module.

The main attraction with HLK-7688A is the switch/router capability. If I connect using Ethernet or Wifi I will need that regardless and having it as part of a control module is very attractive.

HLK-7688A Suit Prolific driver not working

Posted on by Jan

I recently purchased an small dev kit for HLK-7688A (above) and noticed that it has a Prolific USB-to-Serial port. Connecting it I get this message:

Windows detects the port, but the driver will not open it. I assume this is a fake chip issue again. I have had this issue with Prolific before – which is why I try to avoid devices with Prolific on. I will see how I can get around this.

I respect that fake chips are a problem, but it is not my problem! My respond on things like this is that I add Prolific to the list of companies I avoid. 

In this case I might need to grab the UART TTL signals and use a CH340 circuit so I can use the dev kit if I can’t get the Prolific junk driver to work. I will also ask the vendor to ditch Prolific and use CH340 to avoid the problem. In this case I might very well have picked up a copy as this is an open dev kit.

3KW Thunder Stick

Posted on by Jan

This is my 3KW 3-Phase Motor Driver Rev 1.3. Revision 1.0 and 1.1 had air wiring, 3 current sensors and output at right. Rev 1.2 lacked RS485 while Revision 1.3 have CAN and RS485 + 2 temp sensors between MOSFET’s + I solder on cobber wires directly on PCB for 60V and GND to sustain 50-100A. The actual rating for the MOSFET is 160A per MOSFET, but my math indicate we can sustain 50A continuous due to PCB and Heat dissipation.

The VESC (Vedder design) uses more powerfully MOSFET’s, but is also limited to 50A continuous due to heat dissipation. My design allow for a heat-sink on the back. My math indicate that I reach ca 1W dissipation at 35A per MOSFET, so I should be able to sustain 35A continuous on single channel. But, using a 3-phase you have 3 channels and as the limit here is dissipation per MOSFET it should be 35A *3 /2 which is 52,5A before I need a heat-sink. Adding the heat-sink I hope to reach closer to 100A continuous, but you have to take these numbers with a pinch of salt + With 100A continuous (which means average) I might be touching the 160A pulse limit and start overheating PCB lanes – so 50A is the target for a reason – for now. I have seen smaller designs that claim 5KW etc, but they kind of “forget” to mention that you need a shitload of heatsink/fan Attached. My objective is to achieve this with close to no heat-sink due to total size.

I have 3 motors I can test + a 4th on it’s way. Comparing this to the 3KW Universal Driver I have the opposite challenge – I actually could need far more power (Ampere) though this stick to drive more powerfully 3-phase motors available at decent cost.

I have renamed this to 3KW Thunder Stick – size is 100mm x 25mm which is perfect as I get finished heat-sinks and it is more or less an extension to the wires, easy to hide on a drone.

This shows the back-side where the heat-sink will be added. The MOSFET’s and DRV8301 both have pad’s underneath, so the heat-sink will cool them down as well as cool down the PCB itself. All wires (60V, GND and U,V,W will be added on top. power capacitor will be soldered directly on power cables. If heat-sink is not needed I can move the cables to bottom – I can also Mount a Shorter heat-sink on top thought I currently lack mountings holes to support that – but we will see.

I have delayed ordering this PCB because my backlog is so large, but I will order it now so I can test fundamental concepts + mechanical fittings.

Hat Summary

Posted on by Jan

Its been a few Hat’s since I started the latest series using SPI as backbone, so it’s time to consolidate on those I want to finish first. I have a list of close to 40 different Hat’s I want to make. Key to them all is that I use STM32F405 as a reusable component to cover 90%+ of source code – once I have infrastructure and AL on one I basically have it on them all leaving only specialized libraries and a few lines of Hat depending soft-wiring.

  • XPortHub have a lot of the handy interfaces + storage memory and SD Card. This is my current Development base as well.
  • 32 x Servo/IO is mostly needed for Servo control.
  • 8 x DC is small DC motors.
  • 7 x 5 Wire Stepper is very handy for those low cost, small steppers.
  • NB-IoT gives me a way to communicate using global Telecom on very long distance as long as I have GSM, 2G, 3G or 4G coverage.
  • LoRa gives me free up to 12Km range.
  • 12xPWM is very handy for various reasons including solenoids, dc motors, small 3-phase motors and Nema17 style stepper motors.
  • Sensor Hat gives me an interface to various analogue & digital sensors.
  • Wifi & Ethernet Hat is not a priority since it basically cover the same as Raspberry PI, but I like ESP32 to much to not include it on the list + a majority of infrastructure needed here is made.
  • My 60V PSU Hat was not intended as a Hat, but it is a nice option if I use motors and have only one PSU.
  • 3D sensor & GPS is the latest Hat that I have not started on yet. I have GPS on LoRa as well, but decided to add GPS on the planned 3D sensor. I will need multiple of these on the larger drones.

In addition to the list above I have a range of motor controllers of which only one is in Hat format.

  • 3KW Universal Motor Driver
  • 3KW 3-phase motor driver
  • I do in addition have a smaller universal motor driver that I consider upgrading. This only cover ca 15A and is smaller not requiring specialized wiring as the 3KW one. I am a bit undecided on several issues around the Universal Motor Driver as mentioned below.

The 3KW Universal Motor Driver is cool and it’s powerfully as it can be extended with other Hat’s, but I have to consider if this is worth it. I have a new motor incoming to make it possible to test this, but to be honest motors in this category is either extremely expensive or 3-phase – and 50A is not much on a 3-Phase as I easily could need 200A on larger 3-phase drone motors. I like the universal drivers to much not to finish them at some point, but I realize that I am better off focusing on the 3-phase driver for larger motors. It is not many steppes that I can’t drive With the PWM card and even the smaller 250W Universal Motor Driver was troublesome to test. This is a very successfully and fun Project so far, but truth been said I might not have much real usage for it for now.

And lets not forget Raspberry PI that also need software once I am completed with XPortHub that I use as base SW factory.

We are talking about several test projects, but both a boat and airplane is on the agenda. Myself I really want to build an airplane-drone with VTOL capacity – basically take of and land as a drone and fly like an airplane to cover more distance. The showstopper is cost right now. I need a minimum size and that means expensive motor and frame. The boat is far more realistic.

The main challenge with these drones are that they need to be AI driven. As they get further from base communication will be limited and they need a minimum of self-contained navigation intelligence as well as sufficient AI to find their way back home.

Mentioning radio range – Lora is 868Mhz line of sight up to 12Km with a 1W Sender. I actually want to build a radio with larger range using long- or medium- wave signals. An AI based drone can manage with very low bandwidth if it can operate in automated mode only receiving commands and sending data then needed. With a long-range radio on 100Khz you can in theory radio half around the planet on a few watts. The main trouble is size on equipment and licensing to use frequencies.

Wifi/Ethernet Hat

Posted on by Jan

This early draft uses ESP32 and a HR911105A RJ45 connector. I want to attempt using LAN8720A as Phy. The Hat will contain SPI as backbone, CAN as secondary control, an USB, Wifi, Bluetooth and Ethernet.

The schematics look straight forward, but I have a lot of reading up to do.

ESP32 is as fast as many of the modules I have shown and it can be extended to use modules with more Flash and RAM.