XFM2 XVA1 Extended PCB
Please read the disclaimer and the section "important notes" before consdering to use this.
This DIY PCB is designed to offer most of the functionality that the device offers, e.g. control voltage, and it adds some additional functionality like the following:
- Midi out and midi thru. Midi thru is realized through the circuit, not through the FOGA as XFM2, unlike XVA1, does not have a midi thru pin. Midi out and midi thru are going through schmitt-trigger for a clean signal.
- LEDs for midi in, midi out, led audio, led clip. Midi in and midi out LEDs are realized through the circuit, not through the FPGA pins.
- Doepfer A100 connector
- Control voltage that is regulated down to 3.3V for the Cmod A7 via the MCP6004 op-amp. The A100 connector must be used in order for the control voltage pins to work.
- The board uses the H11L1 opto-coupler instead of the 4N36 of the original circuit. In some occasions, I have experienced hanging notes with the 4N36. The signal seems to be more clean through a schmitt-trigger.
- Buffers and logic level conversion for 3.3v and 5v TX/RX UART breakout pins
- On-board USB-to-UART IC with a USB-C connector for serial usage when the A100 connector is used (you must not use the fpga micro-usb connector in this case)
Let me know if you have any questions about any content on this page.
The following notes are important to avoid misunderstandings and wrong expectations. So please read them carefully.
- The board uses a Cypress USB-to-UART IC as the FT232 chips are (currently) hard to source. While it generally works perfectly fine, there is the downside to it that the newer Excel sheets from futur3soundz explicitly make use of the FT232 and not serial in general. So the newer XVA1 Excel sheets do not work with this board through the USB-C connector and an older version of the Excel sheet has to be used (to be obtained from the futur3soundz.com blog where the earlier xva1 release candidates can still be downloaded). The usual Excel sheets can be used if the board is connected and powered through the CMOD A7 connector instead of the external power supply. Be aware that the old Excel sheets aren't perfect. For me, Excel freezes quite often the first time I read a program. This is normal an described in the blog. You can circumvent this by starting a terminal to the serial console first (baudrate 500000) and sending the character 'd' (which is a program dump). After you disconnect from the terminal and load up Excel, reading the programs should work fine.
- I recently discovered that the older Excel sheets do not work anymore at all on my Windows 11 machine. I suspect this happened either due to my update to Windows 11 or some necessary feature has been removed from Office 365. I currently have no solution to make the Excel sheets run again. They may work fine with Windows 10 or some older Excel versions, I do not know yet. In any case, the XFM2 and XVA1 ctrlr panel found on Github can still be used through midi.
- Please never connect any of the power connectors (barrel jack or A100 connector) at the same time as the Micro-USB connector of the CMOD A7. This is pointer all over the CMOD A7 manual. I haven't tried this and don't intend to try it. On the other hand, connecting power through the barrel jack and the A100 at the same time should be safe. The circuit has been designed with this possibility in mind. I suggest not to do it anyway though.
- The PCB does not have built-in thermal management of the smd power regulators through a copper area or similar. As a result, the LM1117 power regulators can run hot depending on the input voltage. I strongly recommend putting small heatsinks on them (see images). Especially, when running the board through the A100 connector using 12V, the regulators will run hot. Also, they may become unstable if they draw too much current through the breakout pins. This also depends a lot on the thermal behavior of the exact lm1117 ic's in use. The regulators I chose for the preassembled jlcpcb boards seem to be, unfortunately, less tolerant to heat than the texas instruments IC's that I have used for the manual assembly. However, with a heatsink on top of the regulators, I have successfully tested powering the board through the 12V A100 connector for more than 24 hours without additional current draw through the breakout pins. If you plan to use the breakout pins to power external displays or similar, be sure to take extra care understanding your current draw, the voltages and test carefully how the board behaves. When in doubt, I suggest to avoid drawing extra current from the xfm2-extended pcb.
- To use the control voltage ports, the A100 connector must be used. The opamp that takes care of scaling down the control voltages for the CMOD A7 requires a negative reference voltage which is not provided when the device is powered through USB or the power jack.
- If you want to use Midi Out with XFM2, you need to use the latest xfm2 beta version from the futur3soundz.com blog. The last stable release unfortunately does not include this functionality.
I have split this part into two sections:
- The first section is comprised of the components that can be assembled by jlcpcb with their lcsc.com component numbers.
- The components in the following table denote the components that need to be soldered by hand based on the board preassembled by jlcpcb. If you want to solder this board completely by hand, you'll have to consider both parts, i.e., the BOM linked above (first section) and the table below.
The following table contains LCSC component numbers where available or otherwise, the components are linked to examples at other dealers. Please note that I tried to reconstruct what I have bought as good as I could. I cannot guarantee at this point that there might be mistakes in the provided examples.
| Quantity | Component | Label | LCSC | Comment |
|---|---|---|---|---|
| 2 | 74LVC1G07QSE-7 | IC1,IC2 | C507244 | |
| 3 | Midi In, Out, Thru | J1,J3,J4 | ||
| 1 | USB4105-GF-A | J10 | ||
| 1 | Pin Breakout 2x10, 2.54mm | J2 | ||
| 1 | Conn_Coaxial | J5 | ||
| 1 | Jack-DC | J6 | ||
| 1 | A-100_Bus_Connector 2x8, 2.54mm | J7 | ||
| 2 | AudioJack2 | J8,J9 | ||
| 1 | CY7C65213-28PVXI | U10 | C134181 | |
| 1 | CmodA7-35T | U2 | ||
| 1 | 24LC10 | U3 | C1348777 | |
| 1 | UDA1334A | U4 | ||
| 1 | MCP6004 | U8 | C7378 | |
| 2 | Heatsinks for the power regulator | These don't fit perfectly, but well enough | ||
| 1 | 2.54mm pin sockets for CMOD A7-35t and the UDA1334A | you can get 2.54 sockets a lot cheaper than this |
In the Gerber directory, there are three relevant files:
- The Gerber ZIP
- The BOM File
- The CPL File
I highly recommend to get this board preassembled as it is a bit of work to solder all the components by hand. You will notice that the assembly instructions do not cover all SMD components. This is because at the time of creation of this board, not all components were available at lcsc.com for assembly. So you will need to have some SMD soldering practice to solder the remaining parts. Some of the remaining SMD components, especially the Cypress IC (U10), the logic level converters (IC1,IC2) and the USB-C connector (J10) might be challenging to solder without a microscope.
- Start with the EEPROM U3 first. After that you can already try to program the CMOD A7 through it's direct micro-usb connector.
- Continue with the flattest components first, i.e., IC1, IC2, J10, U10, U8.
- Solder the through hole components last.
- The Cypress USB-to-UART IC must be programmed using the USB Serial Configuration utility. You can download the necessary USB-Serial Software Development Kit from Infineon. This is also how you get the necessary Windows driver for the IC. You can find the file to be programmed here.
The project is open-source and DIY. You can therefore build your own and even sell them if you want. If you don't want to build one for yourself and are located in the EU, you are welcome to contact me. I may build one on demand if I have the time.