Electronics
Note
The first version of the new SimInvent PCBs has errors. The headers are a bit to narrow to fit the Pro Micro module, it could work by bending the legs a bit. Also the Yoke PCB has the headers to close to each other to fit JST XH headers. Standard DuPont pin headers works fine though.
These errors will be fixed in the next PCB version.
This section is based on the new circuit boards graciously contributed by @PeteDDD. These feature a new optimized design and also integrates the TCA9548 chip as well as having both SMD and through-hole footprints giving the option to use either one.
Please refer to the old Electronics section if you have the old v2.0 Gagagu version of the circuit boards.
Schematics in PDF and SVG formats.
Full KiCad project files here.
The board carries both through-hole and SMD footprints for all the resistors and capacitors, use one of these options depending on your preference.
SMD components
Through-hole components, with TCA9548 module
A number of different connectors can been used. Pin headers, screw terminals or JST XH headers that has a keyed orientation and is reliable (recommended). Any type of header with a pin pitch of 2.54 can be used. You can even solder directly to the board but it is not recommend since wires can sometimes break from repeated bendings and being able to easily replace them is nice. The drawback of using screw terminals is that wires can become loose. And keeping track of which wires goes in what terminal can be challenging.
The panel header connects to the following:
- Power on LED (5V)
- An "error" LED. It is connected in parallel to the buzzer and has the same signalling as the buzzer. The buzzer is used for signalling both positive and negative feedback with the pitch (frequency) of the sound and the LED cannot fully convey that, so it is recommended that a buzzer is used.
- Calibration button
- Reset button. The boot loader in the Arduino Pro Micro has been a bit iffy at times when uploading the firmware. This might be because the processor is busy sending data on the USB serial port all the time. However, if the microcontroller is resetted 2 times within 8 seconds the bootloader will initialize and the upload works every time.
Note
Minus pin to the "flat side" of the LED.
The buzzer must have the correct leg to ground (The positive terminal of the buzzer is normally marked with a '+'). The PCB has two footprint pitches (5 and 6.6 mm) for the buzzer, but it is fine to bend the legs a bit to make it fit. I used an Arduino buzzer module. There are many options as long as it is 5V and a passive model.
The buzzer has an jumper header to enable or disable the buzzer, if one wants to rely on the LED only. The default setup is to have the buzzer always enabled, and the LED is entirely optional.
There is also a trimpot that can be used to control the volume of the buzzer. Default is to set full volume.
The microcontroller can be soldered to the board directly, but it is recommended to use female pin headers or a socket so it can be removed if faulty.
The PCB has two options for the TCA9548 I2C multiplexer chip:
- Using a commonly available TCA9548 I2C module and soldering the module directly on the board
- Soldering the surface mounted TCA9548 IC to the U1 position on the board. This option is to be used also if the board is orderered with components placed and mounted by the factory.
Please note that the R1 resistor need to be removed (desoldered) in order for the module to work with 5V.
The roll patch panel serves to centrally connect all the wiring from the Left and Right IR sensors and the roll encoder of the frame. A common cable is then routed via the cable chain to the main PCB.
This is documented further in the Wiring section
If soldering yourself, places the 16 pcs of 0603 size 10K resistors on their positions. The two 74HC165D smd type ICs are placed accordingly.
Note
Take note of the orientation of the ICs (the dot).
I soldered the wires from the yoke buttons directly, but consider using connectors here as well for a better result.
For the main cable through the yoke tube I would recommend using a connector. A standard pin header (dupont) variant works fine here, JST XH is another option.
Tip
Make the slotted hole in the yoke tube where the cable exits just large enough so you can slide this connector through for easy maintenance when needed.
Please refer to the Yoke Controller section for wiring instructions.
Gagagu has made a detailed documentation of the ordering process of PCBs and mounted components in the older version of the Electronics guide. This can be used as a guideline as how to order, but keep in mind that the new boards has different BOMs.