RED Brick status report

The last time we wrote about the RED Brick is now over a month ago (RED Brick in EMC laboratory). A lot of work has been done in the meantime. We already wrote about the general software infrastructure of the RED Brick. Now we want to give you an update:

Stack communication with other Bricks: The stack communication between RED Brick and other Bricks was a lot more effort than expected. The currently used protocol could not be used, thus we had to change it. The new protocol had to be discarded and reworked several times until we found an implementation that could support the peculiarities of the DMA controller on the RED Brick and still be compatible with the normal Brick microcontrollers. However, we now do have a protocol that is stable, corrects errors and performs well on both platforms.

Ethernet and RS485 Extension: We would like to support these two extensions at sales launch. The Ethernet Extension uses the Wiznet W5200 Ethernet IC. There is no Linux kernel support available for this IC. We were however able to develop a driver based on the similar W5500, which already had a kernel driver in the works by Wiznet. If you now put an Ethernet Extension on a RED Brick stack, the Ethernet Extension will be seen by the underlying Linux as a normal network interface (”eth0”).

RED Brick API Daemon and Brick Daemon: The RED Brick API daemon implements the RED Brick API. It is the interface between the RED Brick and anything external. With this API you can configure the RED Brick. You can upload programs, schedule and execute them. The API Daemon is now nearly done. The Brick Daemon has been extended, besides USB connections it can now also manage serial (RS485 Extension) and SPI (stack communication) connections on the RED Brick.

Brick Viewer: The Brick Viewer is currently still missing lots of necessary features. We still need to implement lots of the features that will be needed to use the RED Brick as a black box. This includes configuring network configurations, hostname, ip address or configurations for the local Brick Daemon (port, authentication, logging). It will be possible to monitor the state of the RED Brick (processes, cpu/memory usage). Extensions need to be configured (baudrate, slave addresses, etc) and much more.

Below you can find a first screenshot of the RED Brick tab in the Brick Viewer:

More hardware hickups: We did already talk about errors in the hardware design. Unfortunately we did not manage to fix all of the bugs in the first go. The datasheet of the processor has a table with the available pins. It shows the available features for each pin (e.g. input, output, etc). Nearly all pins can do input as well as output, according to the table this is also true for “PG2”.

This pin is used in our design by the second extension. Unfortunately we only found out that this pin does not really support output very late in the development. We just couldn’t get the Ethernet Extension working if it was put on the stack as a second extension. We then found a hint about this in the revision history of the datasheet:

In the revision history they say that they changed the pin description for PG2 from Input/Output to Input only. But they only put this hint in the history, they didn’t actually change the table! GODDAMNIT!

What does this mean? We already had the circuit boards for the production run ordered, we couldn’t cancel them anymore. We discussed the issue and came to the conclusion that we can’t sell the first version of the RED Brick with a known bug that prevents the usage of a second extension. This would not affect a huge amount of applications, but it just does not comply with our standards regarding quality.

We will use the circuit boards with the bug on them to do another test run of the RED Brick production. We will then be able to test the hardware extensively, since we will have lots of prototypes. After that we will order new circuit boards and we are now planning the production for the beginning of December, so that we can start selling RED Bricks before Christmas.

Stay tuned!

New cheaper LED strips

As of today we have new WS2812B LED strips in our shop. You can now buy 5m strips for 59.99€ (incl. VAT). The old WS2801 LED strips had a price of 99.99€!

The strips have 30 RGB-LEDs per meter (previously 32 LEDs). The controlling IC (WS2812B, sometimes called “NeoPixel”) has the LEDs directly integrated. The strips can be controlled by the LED Strip Bricklet. You only have to connect 5V, ground and one data line. The strips with WS2812B are cheaper to acquire for us and we are of course sharing the price advantage with you!

We will only offer full reals of length 5m with the new strip type. The effort to create strips with custom length does not make a lot of sense anymore with the new retail price.

RED Brick in EMC laboratory

Yesterday we were in an EMC (electromagnetic compatibility measures) laboratory.

We did an preliminary EMI (electromagnetic interference) test of the RED Brick prototype. As a first test we put the RED Brick alone without any other components in the chamber. The RED Brick was running and just doing CPU cycles on its own.

The result was phenomenal! It was beyond our expectation, during the run we temporary thought that something with the test chamber was not in order. But it turns out that everything worked and the RAM, oscillator and similar are routed very well. They nearly don’t show up at all!

As a next test we tested a stack comprised of Step-Down Power Supply, RED Brick and Master Brick.

Here you can clearly see the SPI stack communication, since all of the peaks are a multiple of 9MHz (the frequency that we use for SPI). However, the result is still very good.

The green line is the absolut maximum measurement, while the magenta line is an average. For the real measurements that we will do with the final version of the RED Brick the quasi-peak will be measured. This will lie somewhere in the middle of both lines.

Unfortunately we were not expecting the phenomenal result of the RED Brick alone, so we weren’t well prepared for the stack tests. The RED Brick has resistors in the SPI traces that can affect the edge steepness. The RED Brick that we used for testing had 0 ohm resistor soldered in place. The next time we are in the EMC laboratory we will try out different resistor values to further decrease the interference that comes from the SPI communication.

However, all in all we can now already be completely sure that we will be able to issue a CE certificate for the final version of the RED Brick. This is very good news, we weren’t even expecting results this good!

We will now be able to order circuit boards for the next prototype. We hope that this prototype will already be the final version of the RED Brick. In the new prototype we incorporate the following changes:

  • Reset button is now connected to GPIO and will halt the Linux properly.

  • We can now reset the stack that is on top of the RED Brick via software, this makes it possible for brickd to restart the stack when it is started the first time to get the Bricks in a known state.

  • JTAG hardware is now configured correctly.

  • We use an inverter on the serial RTS line and fix CTS to ground to be able to control the RS485 Extension more easily.

  • Fix wrong wiring in power supply.

  • Pick-and-place-ability improved.

  • USB ESD protection circuit error fixed.

After these test results we are confident that we will have the RED Brick in our shop this year. So stay tuned!

MakerBeam at Tinkerforge

As of now you can by MakerBeams in our shop! It is the perfect mounting solution for Bricks, Bricklets & Co.

MakerBeam is a versatile and lightweight structural system with a cross section of 10x10mm. It has endless building possibilities in desktop size and uses Mini-T, which is a smaller version of the T-Slot standard that is widely used in industrial automation. Each beam has a 8mm deep 2.5mm diameter threaded hole on both ends, sized for normal M3 screws. The profile system is very light, each millimeter of beam has a weight of only 0.136g. You can use MakerBeam to build the mechanical structure for robots, CNC projects, camera sliders and other cool projects! The official MakerBeam website has a big list of example projects.

With MakerBeams we are extending our range of accessories. As a next step we want to add motors (stepper, servo, dc). We are currently testing different motors from different manufacturers, stay tuned!

As soon as we received the first beams and brackets we of course had to start tinkering with them immediately ;-). We were able to mount different Bricks and Bricklets into a frame in no time:

This thing would be doing well as a satellite, don’t you think?

New Bricklets: Color, NFC/RFID and Solid State Relay

We used your feedback to design three new Bricklets. All three of them have been released today including lots of accessories:

1) Color Bricklet

The Color Bricklet uses a precision color sensor. The sensor can measure RGB color, color temperature and Illuminance with a resolution of 16 bit each! It is possible to enable a defined lightning (by an LED) via software. Using the LED makes it possible to measure the light reflection of an object with high precision and repeatability. A usage for the Bricklet is for example the sorting of objects. While the Ambient Light Bricklet can measure up to ~1000 Lux, the new Color Bricklet can measure values of several 10000 Lux without any problems.

2) NFC/RFID Bricklet

With the NFC/RFID Bricklet you can read and write different 13.56MHz NFC or RFID tags. The Bricklet supports Mifare Classic, NFC Forum Type 1 and 2 RFID/NFC tags with an arbitrary amount of memory. Suitable tags in the form of cards, keyfobs and stickers can be found in our shop. As an example you could build an intelligent cat door with this Bricklet. It could log the enter/leave times, twitter it and similar :-). We have lots of ideas for interesting projects for this product! This example is also good to explain an important feature of NFC: The range is limited to 10cm. The cat door should of course not open itself if the cat is only roughly in the vicinity.

3) Solid State Relay Bricklet

Switching big loads, such as motors, can be problematic. Currently it is possible to use the Dual Relay Bricklet to switch voltages. But especially big 230V loads can be problematic if switched with a mechanical relay. Switching sparks can easily lead to unstable systems. In this case it is possible to use a Snubber (see Dual Relay Bricklet documentation). It is however easier to use a solid state relay. A solid state relay does not switch mechanically, it is a completely electronic switch. Thus there are no switching sparks present whatsoever. A solid state relay also has more switching cycles (it is wear-free) because no mechanical parts are used. It also has a galvanic isolation between the controlling (input) and the load (output).

It is very easy to switch these relays with the Solid State Relay Bricklet. We are offering two different types of relays. One can switch alternating current of up to 25A at 380V and the other can switch direct current of up to 50V at 80A. Additionally we have a cover that can protect you against touching the contacts as well as a heatsink that is necessary if you want to switch big loads.

We tested different types and manufacturers of solid state relays. Please note that the relays in our shop are of high quality compared to some of the super cheap relays that can be bought in china. Although the Bricklet might be compatible to these super cheap relays (at least if you solder a wire to it), we would highly recommend to not use a 2$ relay. We learned our lesson while testing a cheap solid state relay with our electronic load.