I’m planning on building some DIY low-budget hydraulic pedals and originally wanted to reward myself with a DD-wheelbase when finished with the project. Since I’m not using a load-cell (but a 0.5-4.5V pressure sensor), I was struggeling to find - or in the worst case build - an interface with an appropriate resolution (16 bit).
Coming across the Simucube 2 and finding out about its accessory port this might bring my search to an end regarding the interface and the wheelbase, but I have two questions regarding the analogue inputs:
Do the inputs really have a resolution of 16 bits from 0-5V or is it somewhat upscaled?
To layout my electronics properly - How high is the impedance/resistance of each analogue input?
Thanks a lot!
Leo Bodnar has a very good 16-bit interface board for load-cells.
From what I found at LeoBodnar they have a 16 bit interface only for load cells. The “normal” joystick interface is only 12 bits. My pressure sensor outputs 0.5 Volts at 0 pressure to 4.5 Volts at max. pressure when supplied with 5 Volts. So imho there is no need for load-cell amplification. I was hoping to not need a separate interface at all when using the accessory port.
If your pressure transducer is standard 3-wire analog output, then it can directly interface to the accessory port on the SC2.
For 4-wire sensors like I am using on my hydraulic pedals, a LC interface is required. As such, I had to use 2x Leo 16-bit boards, as I have both clutch and brake 4-wire Measpec transducers, luckily my throttle is using an LVIT with std analog output.
Anyway, I know Measpec also have available transducers with std analog signalling, but they are very pricy…So it is always more cost-effective to get the 4-wire sensors and marry them to Leo’s 16-bit boards, imho.
Anyway, this is the 16-bit Leo board I am using, all channels on it have EMI-protected inputs and are16-bit resolution - http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=94&products_id=297
Hopefully it helps.
Thank you for the detailed information. My sensor is a 3-wire one and with around 20 bucks rather cheap. Hopefully the signal is not too “spikey”, otherwise I’ll have to upgrade to a more expensive one. For the clutch the hydraulics are just for the feeling. The pedal travel will be taken with a potentiometer just like the throttle.
Do you have any info on the impedance of the analogue inputs of the accessory port?
I would have to have a look at schematics to get that information to you. If you really need that information which nobody has asked us before, I would advice to write to our support.
Thanks for the advice, I’ll reach out to the support with my question. The reason I’m asking is to select the proper potentiometers respecticvley their resistance for throttle and clutch. Any recommendations on that?
Typical pot values are 10k, get good quality pots though. Perhaps you can look into hall-effect sensors for the throttle too.
But if you do use pots, search for Bourns or other high-quality units.
Thanks a lot!
For the throttle I want to use a real throttle body (respectively its potentiometer) operated by a bowden cable, but have to measure the resistance yet. For the clutch I’ll look out for Bourns.
I made an inexpensive pedal set with a hydraulic brake and pressure sensor like you mentioned. I modified Lebois Racing’s pedal design to use a Hall sensor instead of a potentiometer and can confirm that both the brake pressure sensor and accelerator hall sensor work very well plugged into the Simucube accessory port. It is simple to set up the start and end zones and I don’t have any trouble with spiking.
Interestingly, when I tried to make an adapter for my old Logitech G27 pedals, this didn’t work properly. Though I could configure them in the Truedrive software, the brake would only work if the accelerator was also pressed at least a little. Not sure if this is something to do with the way that the logitechs are configured or if I crossed a wire somewhere! Doesn’t matter now though, the new pedals are far superior and a better match to the simucube.
Thank you for bringing Lebois pedals to my attention. I’m planning something similar but not with 3D-printed pedals but a “real” pedal box for motorsport purposes from OBP (for a Super-7 if I’m not mistaken). For the brake I also want to use a real caliper stuffed with metal sheets and a layer of rubber to take the force/pressure.