Gateway device
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I've started using KiCad for this project.. Still it's far from completed (things are progressing more slowly with this one, than the last, as it's a bit more complex and I don't have that much time at hand now..
Anyway, I have created a github repository of it, if anyone wants to have a look, https://github.com/tbowmo/MySensorGW
Current schematics are here (PDF file)
MySensorsGW-schematic.pdfIt's still a Work In Progress.. A lot of stuff needs to be ironed out..
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There will eventually be footprints on there for wifi / ethernet modules.. And Yes I2C should go to a pinheader. SPI is already at a pinheader (kindof). As it's connected to the ISP header :)
I'm trying to get a grip on my thoughts, and create some parts for wifi/ethernet modules.. :)
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So decision time..
For wired ethernet, it seems that we have 2 options:
- w5100
- enc28j60
I haven't got that much experience with theese devices, so which one should we go ahead with?
Wireless, I think that I am settled with esp8266, but if there are anything else out there, that might be better, then please let me know..
At the moment I can't really decide which one is better :) So need some help from the community.
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I use the W5100 on my current gateway, and I have not had any significant issues with it (apart from the infamous SPI issue, which is resolved by controlling the SPI_EN signal to the W5100. Apart from that I am happy with it, and it is intelligent enough to allow the necessary software to fit an Arduino Nano. Unfortunately not with DHCP enabled (and signing support enabled). But if the enc28j60 does not require more software, and handles SPI(?) "properly" perhaps it would be the better alternative?
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@tbowmo thank! it is a good job done!
some questions/comments- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
do you think it is needed? what kind of the shield your are looking for? - why not to put 20MHz crystal to give some more performance to the gateway?
- USB is normally can supply not more than 500mA, are you sure it will be sufficient? DC-jack probably will be also good to have. ESP+wisnet could be hungry for the supply
- why atmega1284? it is not a standard arduino choice but could costs on a level of 1280. atmega128 is the lowest cost 128k AVR. If we are sure 128k will be sufficient in the future I will select atmega128 because of cost or atmega1280 because it is standard for arduino
And also I will consider atmega2560 to have a maximum possible resources (not only flash but also RAM)
sense and drive
- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
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@tbowmo thank! it is a good job done!
some questions/comments- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
do you think it is needed? what kind of the shield your are looking for? - why not to put 20MHz crystal to give some more performance to the gateway?
- USB is normally can supply not more than 500mA, are you sure it will be sufficient? DC-jack probably will be also good to have. ESP+wisnet could be hungry for the supply
- why atmega1284? it is not a standard arduino choice but could costs on a level of 1280. atmega128 is the lowest cost 128k AVR. If we are sure 128k will be sufficient in the future I will select atmega128 because of cost or atmega1280 because it is standard for arduino
And also I will consider atmega2560 to have a maximum possible resources (not only flash but also RAM)
@axillent said:
@tbowmo thank! it is a good job done!
some questions/comments- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
do you think it is needed? what kind of the shield your are looking for?
I was looking at the cheap Chinese breakout boards with W5100 chip on, not all of them have the SPI fix onboard, so that's why I implemented it.
- why not to put 20MHz crystal to give some more performance to the gateway?
Hmmm.. think it was a price thing.. 16Mhz was more common than 20Mhz. But can't remember it right now (it's been a couple of weeks since I put in the 16Mhz xtal)
- USB is normally can supply not more than 500mA, are you sure it will be sufficient? DC-jack probably will be also good to have. ESP+wisnet could be hungry for the supply
In my thoughts, it should be either W5100 or ESP8266 mounted, not both at the same time (since both is for "internet" access. Also, most phone chargers are delivering 1A and up. Also, if you connect the thing to a computer via USB, you might not want to use W5100 / ESP8266 to communicate with it, so those power eaters could be left out in that case, leaving only NRF and/or RFM69 as radios.
- why atmega1284? it is not a standard arduino choice but could costs on a level of 1280. atmega128 is the lowest cost 128k AVR. If we are sure 128k will be sufficient in the future I will select atmega128 because of cost or atmega1280 because it is standard for arduino
There are some people that are using atmega1284 with arduino IDE, so it can be used. Solderability is the first reason: atmega1280 is 100pins, while atmega1284 is 44 pins, price: atmega1280 is 15.96$, while atmega1284 is 8-9$. Of course I can see the point in putting in 1280, as it could be swapped for a 2560 if more flash/ram is needed.
And also I will consider atmega2560 to have a maximum possible resources (not only flash but also RAM)
Atmega1280 is pincompatible with atmega2560, so they are interchangeable.
Anyways, this is mainly playing around with KiCAD, and creating something that might be usefull along the road :). Design is not locked yet, so I'll take a couple of iterations on it (just like I did on the sensebender micro, with selecting powersource, and sensor types).
- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
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@axillent said:
@tbowmo thank! it is a good job done!
some questions/comments- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
do you think it is needed? what kind of the shield your are looking for?
I was looking at the cheap Chinese breakout boards with W5100 chip on, not all of them have the SPI fix onboard, so that's why I implemented it.
- why not to put 20MHz crystal to give some more performance to the gateway?
Hmmm.. think it was a price thing.. 16Mhz was more common than 20Mhz. But can't remember it right now (it's been a couple of weeks since I put in the 16Mhz xtal)
- USB is normally can supply not more than 500mA, are you sure it will be sufficient? DC-jack probably will be also good to have. ESP+wisnet could be hungry for the supply
In my thoughts, it should be either W5100 or ESP8266 mounted, not both at the same time (since both is for "internet" access. Also, most phone chargers are delivering 1A and up. Also, if you connect the thing to a computer via USB, you might not want to use W5100 / ESP8266 to communicate with it, so those power eaters could be left out in that case, leaving only NRF and/or RFM69 as radios.
- why atmega1284? it is not a standard arduino choice but could costs on a level of 1280. atmega128 is the lowest cost 128k AVR. If we are sure 128k will be sufficient in the future I will select atmega128 because of cost or atmega1280 because it is standard for arduino
There are some people that are using atmega1284 with arduino IDE, so it can be used. Solderability is the first reason: atmega1280 is 100pins, while atmega1284 is 44 pins, price: atmega1280 is 15.96$, while atmega1284 is 8-9$. Of course I can see the point in putting in 1280, as it could be swapped for a 2560 if more flash/ram is needed.
And also I will consider atmega2560 to have a maximum possible resources (not only flash but also RAM)
Atmega1280 is pincompatible with atmega2560, so they are interchangeable.
Anyways, this is mainly playing around with KiCAD, and creating something that might be usefull along the road :). Design is not locked yet, so I'll take a couple of iterations on it (just like I did on the sensebender micro, with selecting powersource, and sensor types).
@tbowmo 20mhz should cost very similar to 16mhz, price is not an issue in this choice. Frequency is one of the parameter you will need to put inside boards.txt, it could be no issue to replace 16 by 20
ok I see. if soldering is an issue there is also atmega1281/atmega2561 pin compatible having TQFP64 package while been fully compatible with atmega1280/2560 (they do have single datasheet). Their maximum xtal is 16mhz
sense and drive
- w5100 SPI fix is already inside modern arduino ethernet shield http://www.arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf
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@tbowmo 20mhz should cost very similar to 16mhz, price is not an issue in this choice. Frequency is one of the parameter you will need to put inside boards.txt, it could be no issue to replace 16 by 20
ok I see. if soldering is an issue there is also atmega1281/atmega2561 pin compatible having TQFP64 package while been fully compatible with atmega1280/2560 (they do have single datasheet). Their maximum xtal is 16mhz
As I said, I can't remember why I decided on the 16MHz crystal... it could have been a decision based on baudrate accuracy. But I'm not sure now.
one thought, is the arduino spi library capable of using the extra spi ports on the atmega1280? (The 4 uarts can be reconfigured as spi ports)
Started debating with myself, the benefits of changing cpu :) I'll look further at the data sheets.
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As I said, I can't remember why I decided on the 16MHz crystal... it could have been a decision based on baudrate accuracy. But I'm not sure now.
one thought, is the arduino spi library capable of using the extra spi ports on the atmega1280? (The 4 uarts can be reconfigured as spi ports)
Started debating with myself, the benefits of changing cpu :) I'll look further at the data sheets.
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why you need 5 SPI's?)
Just a thought on versatility, that's all :) you could have ethernet hanging on one SPI channel, and NRF / RFM on another, giving higher throughput (Ok, I know that it might not be necessary in this project at the moment..)
Btw. just had a look at the datasheets for atmegas. 1280 / 2560 / 1281/2561 has 8Kb ram, while 1284 has 16Kb. Also operating frequency, 1284 is specified up to 20Mhz, while 1280/2560 etc. is only 16Mhz.
So many parameters to choose from :)
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why you need 5 SPI's?)
Just a thought on versatility, that's all :) you could have ethernet hanging on one SPI channel, and NRF / RFM on another, giving higher throughput (Ok, I know that it might not be necessary in this project at the moment..)
Btw. just had a look at the datasheets for atmegas. 1280 / 2560 / 1281/2561 has 8Kb ram, while 1284 has 16Kb. Also operating frequency, 1284 is specified up to 20Mhz, while 1280/2560 etc. is only 16Mhz.
So many parameters to choose from :)
@tbowmo said:
giving higher throughput
ohh) the logic coming from PC world not working here. regardless how many SPIs you will initiate MCU will handle them in a sequence.
but any way it could be a benefit
for example you can avoid SPI fix if there will be exclusive SPI port used for wiznetSo many parameters to choose from :)
on other hand it is good. atmega644/1284 are from later generation having more features. 16k RAM is a very good thing, gateway potentially could be hungry on RAM usage. The disadvantage is missing 256k version
for last resort I will ask @hek to request quotes from partners to understand better the price difference.
sense and drive
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@tbowmo said:
giving higher throughput
ohh) the logic coming from PC world not working here. regardless how many SPIs you will initiate MCU will handle them in a sequence.
but any way it could be a benefit
for example you can avoid SPI fix if there will be exclusive SPI port used for wiznetSo many parameters to choose from :)
on other hand it is good. atmega644/1284 are from later generation having more features. 16k RAM is a very good thing, gateway potentially could be hungry on RAM usage. The disadvantage is missing 256k version
for last resort I will ask @hek to request quotes from partners to understand better the price difference.
@axillent said:
@tbowmo said:
giving higher throughput
ohh) the logic coming from PC world not working here. regardless how many SPIs you will initiate MCU will handle them in a sequence.
as they are in HW, they operate independently. So you can have two channels receiving at the same time, and another transmitting. The CPU just needs to put the bytes into the tx buffers, and pick up from the RX buffers.
but any way it could be a benefit
for example you can avoid SPI fix if there will be exclusive SPI port used for wiznetYes, when I started looking at the GW, I had in mind using multiple SPI ports just for this. I know that we can use Soft SPI, but i would rather have it as HW implemented as it would offload the MCU for handling the SPI signals.
Anyway, the SPI fix is a single gate that is placed on the board. the cost is at 0.5$ as far as I remember (mouser prices).
So many parameters to choose from :)
on other hand it is good. atmega644/1284 are from later generation having more features. 16k RAM is a very good thing, gateway potentially could be hungry on RAM usage. The disadvantage is missing 256k version
for last resort I will ask @hek to request quotes from partners to understand better the price difference.
I had thought about the same, asking our HW partners in china for the price differences.
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Looking Good!
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I just ordered both ESP8266-01, and a W5100 breakout board, of the types that I think would be usable in this design (Both of them are available from iTeadstudio btw). Just to have some mechanical samples that I can measure dimensions, and connector placements.
So will wait for them to arrive from China.. I will also try to fit everything on one side of the PCB, right now I have an FTDI chip, and a capacitor on the backside (besides a footprint for the RFM69 pcb, which is up to the end user to mount).
ATSHA204 will be a mandatory part of the design anyways. We can just as well put in some security measures in our designs.
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Just tried to create a new stanza in the boards.txt file, defining a board with an atmega1284p MCU. Seems like arduino accepts it, as I am able to use Serial1.begin(); in my code. If I switch back to compile it for a standard atmega328p target, it fails on Serial1.begin(). Also Serial2.begin() fails on atemega1284p target, so this indicates to me that it knows about this CPU from the beginning.
So from an arduino point of view, there is no problem in using atmega1284(p) as target device. (I haven't got one on hand, so can't do any specific testing besides trying to compile things).
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Just tried to create a new stanza in the boards.txt file, defining a board with an atmega1284p MCU. Seems like arduino accepts it, as I am able to use Serial1.begin(); in my code. If I switch back to compile it for a standard atmega328p target, it fails on Serial1.begin(). Also Serial2.begin() fails on atemega1284p target, so this indicates to me that it knows about this CPU from the beginning.
So from an arduino point of view, there is no problem in using atmega1284(p) as target device. (I haven't got one on hand, so can't do any specific testing besides trying to compile things).
@tbowmo sure
in general arduino can handle any AVR8 from atmel
my comment was about "not a standard arduino MCU" means it is not described inside official board.txtif i'm not mistaken atmega644 (same family as atmega1284) is used in reprap and it is arduino too
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Hi,
this is my first post and I've pointed here by @hek while discussing of MySensor and Souliss (that is a project similar and different at same time from MySensor).
Just yesterday we got Souliss running on ESP8266 thanks to the porting of the Arduino cores on that MCU, this is an option that in my opinion you should take in account. The use of ESP8266 (and generally of all other) as WiFi to USART isn't impressive, I've never been in love with AT commands and I prefer binary communication compared to ASCII, but generally your AVR USART became your bottleneck.
Compared to SPI, USART isn't a master/slave protocol and the communication is driven by the transceiver, this is a really mess. When you use SPI, your low-RAM AVR decide when read data and this allow you to use the RAM of the transceiver as an external buffer, the tranceiver has mostly more RAM than the AVR.
While running over USART, the transceiver send data when want, so you should care on the AVR of buffering and process the frame only once is complete.More, the ESP8266 has multiple firmware release that doesn't provide a consistent behavior, so you end-up with a your own firmware to bridge data to USART. But once you need to program the ESP8266, you are just a step away to load on it the whole code.
Hope that this can help.
Regards,
Dario.
