This board has been designed as a specific USB programmer shield for the LHCreate eco-system.
The concerning µ-controller board was fit with an ICSP-connector for programming through various programming devices. When using a µ-controller with proper bootloader, the system can also be programmed serially, by using below described shield. The USB programmer shield acts as a USB-to-serial converter.
The shield has been designed to mechanically fit on top of the µ-controller board by using the available connectors in the central square. These connectors contain all required electrical signals : RX, TX, reset, GND and +5V. The serial converter's DTR-line takes care of the reset signal to launch the bootloader. The shield transparently feeds through the signals from the I2C and ICSP connectors on the µ-controller board. They can be used as if the shield was not there (except during the uploading of new firmware of course).
- have a need
- decide on what is should look like
- build prototype electronics
- design a descent electronics board
- build the final electronics
- test and validate the final USB programmer shield
- write end-user documentation
The CH340G USB-to-UART chip is the central component for this board. Crystal X1, together with load capacitors C3 and C4 will provide a stable clock to the chip. C1 and C2 stabilise the 5V power supply, which will either come from the USB connection, or from the underlying eco-system's µ-controller-board. R1, D1 will light up when the board is powered. C6 has been added for the 3V3 power-line coming from the CH340G chip (not used in this configuration). Through C5, the USB-to-UART chip will sent a reset signal to the µ-controller to be programmed, by means of its DTR line. Reset button S1 has been repeated on the programmer board for accessibility reasons. Pull-up resistor R2 is optional, and only needs to be mounted when the programmer-board is used as stand-alone to program minimal circuits (which have not been fit with such a resistor). R6/D2 and R5/D3 will blink when communication is on-going over the serial connections (RX and TX). R3 and R4 protect the serial connection on CON3 against over-current. I2C connection CON4 can be used transparently when the programming shield is fit on top of the µ-controller board. ICSP header CON2 can be used when the µ-controller is running (not during serial programming). The same applies for the serial connections on CON3.
| Part | Value | Package | Description |
|---|---|---|---|
| R1 | 2k2 | 1206 | resistor |
| R2 | 10kΩ | 1206 | resistor |
| R3, R4, R5, R6 | 1kΩ | 1206 | resistor |
| C1 | 10µF/16V | Panasonic type B | polarized capacitor |
| C2, C5, C6 | 100nF | 1206 | capacitor |
| C3, C4 | 22pF | 1206 | capacitor |
| D1 | green-3mm | 3mm | LED |
| D2 | red | 1206 | LED |
| D3 | yellow | 1206 | LED |
| IC1 | CH340G | SSOP-16 | USB to serial interface chip |
| S1 | momentary | 6x6x6mm | momentary tact push button |
| X1 | 12MHz | SM49 | crystal |
| CON1 | mini-USB | mini-USB | mini-USB connector |
| CON2 | 2x3 (boxed) | 2x3 | AVR ISP-6 serial prog. header (long-needle F-M) |
| CON3 | 3-pin | SIL03 | pin header (long-needle F-M) |
| CON4 | 4-pin | SIL04 | pin header (long-needle F-M) |
The shield has been designed to fit on the LHCreate eco-system µ-controller board, by using its connectors for ICSP, I2C and serial communication. For that matter, long-needle connectors need to be used. These connectors are of female type on the solder-side of the PCB, and have long pins pointing upwards on the component-side. This way all connections remain available during programming and debugging.
The best way to populate the PCB, in case of hand-soldering, is to start with the IC1, as you will need access to the surroundings to remove the excess solder with some braided shielding wire. Next all 1206 package SMD components can be mounted (resistors and capacitors). Mind the polarity when mounting led's D2 and D3. Now you can mount the aluminium capacitor C1 (look at the footprint for the correct orientation), and crystal X1. After having finished with the SMD components, some through-hole components need to be mounted. First the mini-USB connector CON1. The metal housing needs to be solder on the component-side of the PCB, and the five pins from the solder-side. Now, only led D1 and reset-button S1 have to be mounted (solder on the solder-side). To finish, fit the stackable headers (CON2,CON3,CON4) on the LHCreate µ-controller board, and then place the programmer shield in its operational position. The thirteen pins can now be soldered on the component-side (firmly push the PCB down).
If you are having any good suggestions, just drop me a line 📧. If feasible, I'll be happy to implement proposed improvements. And if you are having lots of time, I'll be happy to share the work with you ;-).
When you create your own version, don't forget to send us some nice pictures of your construction. We'll be happy to publish them in the 🎊Hall of Fame🎊.
At this moment, there is no specific license attached to this project.
So, today, if you like it, have fun with it (at your own risk of course :-D), and especially, be creative.
Oh, and when using anything from this repository, it is highly appreciated if you mention its origin.
If you would like to use any of this work (or the whole project) for commercial use, first contact us 📧, so we can add the appropriate license, which best fits your business.