| Electronics > Projects, Designs, and Technical Stuff |
| Sencore USB Interface Project |
| (1/6) > >> |
| pigrew:
I'm developing a USB interface for various Sencore test equipment (such as their LC102 meter). Their used I/O interfaces (like the IB78) are getting pretty rare and expensive, so I figured I should make something a bit more modern. STATUS: PCB and components have been ordered. FPGA logic development is in progress. The prototype PCB is posted at GitHub[url]. If you're interested in buying one (either assembled or as a kit), send me a PM. Original Post: Another reason I want one is that a LC102 asks you to use a special stick to hold down a front-panel button to do burn-in tests of capacitors, but with an I/O interface, one can just ask it to do burn in and also log data. I'd greatly appreciate any comments on the schematic (or even layout) before I order boards. Also if any others are interested in the product, let me know. I can easily sell/distribute (bare PCB+8243) to folks in the USA (I'm not sure what shipping costs to foreign countries). If there is a huge interest, I may even look into having JLCPCB do assembly for me. The genuine interface boxes are based on an 8243 I/O expander and a microcontroller. I've reimplemented it using a 8243 (discontinued but available on eBay) and a STM32 microcontroller. The genuine boxes are not isolated which leads me to have some safety concerns due to the LC102's ability to output a floating 1000 V, with the I/O interface ground connected to the instrument's negative output. Therefore, I've added isolation to the design. Though, I use a 0.1" pin header between GND and EARTH which isn't enough separation, but at least it will be an arc to earth (I also have a shorting terminal for connecting the USB shield to the Sencore's earthed shield). In order to support hot-plug, I've also added a bus switch IC with "I-off" support. The genuine box could crash the meter's MCU bus if plugged in with the box unpowered. The PCB is designed to fit into a Bud HP-3652-B enclosure. I'm planning to have the I/O cable just running through the back panel, though I could switch it to being connectorized. Adding a 0.150"mm pitch Phoenix Contact 1803332 header on the back, but it's a bit large for the enclosure. Other suggestions? There always seems to be conflicting advice on if the USB shield should be shorted to its GND on the downstream side. I'm leaning towards yes, though I've marked it as a capacitor to couple them on the schematic. |
| HighVoltage:
Very interesting. So, this will plug in to the RS232 connector on the back? Will also work on the LC103? You will also provide windows software to control the instrument? Can you also implement it in such a way that it can be used to calibrate the LC103? |
| coromonadalix:
@pigrew super job you did, no pun intended, i would do a single sheet schematic for clarity purposes. |
| pigrew:
Hmm, just noticed there is a IB78 on eBay for $140, but that's what I'm aiming to recreate, but with isolation and USB instead of RS232. --- Quote from: HighVoltage on August 21, 2019, 05:13:38 pm ---Very interesting. So, this will plug in to the RS232 connector on the back? --- End quote --- No, this is designed to go interface with a circular DIN-8 connector on the back of the LC102, which is a 8239 MCU expansion interface, not RS232. My design will act as a USB CDC device (virtual COM port). It replaces the need for an IB78/IB72. --- Quote from: HighVoltage on August 21, 2019, 05:13:38 pm ---Will also work on the LC103? --- End quote --- I don't have a LC103, so cannot test it with one. It looks like the LC103 has a DE-09 connector. I don't know the pinout or even what sort of interface the LC103 uses. I except it will not be compatible. EDIT: Most certainly will not work. I found the schematics of the LC103 and it is RS-232. You could just get a normal USB->RS232 cable and use it to talk to the meter (if you can figure out the command syntax). Be careful with the high voltages, an isolated RS-232 adapter is a good idea. --- Quote from: HighVoltage on August 21, 2019, 05:13:38 pm ---You will also provide windows software to control the instrument? --- End quote --- No, I'm planning to only make the hardware to provide a serial port for the meter. --- Quote from: HighVoltage on August 21, 2019, 05:13:38 pm ---Can you also implement it in such a way that it can be used to calibrate the LC103? --- End quote --- Doubtful. My suggestion would be to make a ROM dump and try to disassemble the microcode to figure out the calibration commands. The LC102 has published commands for its control, as do their older products. LC102 calibration is by adjusting pots/capacitors. |
| coromonadalix:
Would it be feasible with an bluepill STM32F103C8T6 (128 KB flash, 20 KB RAM) for a 2$ usd board Build a daughter board with the other components and the upd8342 ... https://alselectro.wordpress.com/2018/11/18/stm32f103-bluepill-getting-started-with-arduino-core/ The yellow underlined are 5v tolerant ports ?? thks EDIT Found this puppy : https://medium.com/swlh/super-blue-pill-like-stm32-blue-pill-but-better-6d341d9347da at around 6$ usd ?? |
| Navigation |
| Message Index |
| Next page |