fairplay Posted September 3, 2010 Report Share Posted September 3, 2010 ...attn: electronic&MIDIbox-dummy question...i have browsed backwards to find an answer, but did not find anything suitable... ...i'd like to use a joystick as input for a MIDIbox 64 - unfortunately that joystick is just available with two 100kOhm poti installed; now i assume that the AIN-module should work with those also - in terms of: not requiring 10kOhm - but i am not sure... ...could someone either confirm that it would work (even with less accuracy) or tell me if i have to solder a 11kOhm-resistor in parallel to get almost 10kOhm?... TIA. Quote Link to comment Share on other sites More sharing options...
TK. Posted September 3, 2010 Report Share Posted September 3, 2010 according to the pic datasheet the input resistance shouldn't be higher than 10k, on the other hand i know that people used 100k joysticks before and didn't complain. it could happen that sometimes (e.g. depending on ambient conditions like temperature, etc.) CC values will start to jitter, but mostly this doesn't really hurt (e.g. as long as your application doesn't start to record automation data on value changes). adding a 11k resistor in parallel won't help (leads to nonlinear curve), reducing resolution would help to avoid any jitter, but i would propose to start with the default resolution. best regards, thorsten. Quote Link to comment Share on other sites More sharing options...
fairplay Posted September 3, 2010 Author Report Share Posted September 3, 2010 ...hi Thorsten, thank you for your quick and encourageing reply!... ...i did fear that it might not be as easy as to just add the 11k resistor - but then: electronics is a huge new field for me... ...i'll let you know if it works out with the un-altered joysticks - unfortunately i will not have it ready until mid october (you know :ahappy: ) to let you have a try... cu Quote Link to comment Share on other sites More sharing options...
fairplay Posted September 3, 2010 Author Report Share Posted September 3, 2010 ...hmmm, i just realise that your answer relates to the PIC... ...is it the same with STM32 (which i plan to build as i have the parts here already :rolleyes: )... Quote Link to comment Share on other sites More sharing options...
TK. Posted September 3, 2010 Report Share Posted September 3, 2010 probably nobody tried this with a stm32 before. there is the danger for even more jitter due to the reduced voltage range (0..3,3v)... but stm32 has much more internal sram than a pic, so that it would be a no brainer to add individual resolution parameters for all AIN inputs. however, i will try a 100k pot and report results once i'm back home (next week, so early enough before october ;) best regards, thorsten. Quote Link to comment Share on other sites More sharing options...
TK. Posted October 16, 2010 Report Share Posted October 16, 2010 ...i'll let you know if it works out with the un-altered joysticks - unfortunately i will not have it ready until mid october (you know :ahappy: ) to let you have a try... here the just-in-time reply (you know :ahappy: ;) I haven't found 100k pots, so that I used 100k trimpots, but they shouldn't make a big difference. As long as I don't touch the middle pin, pot values are stable. Once I put my finger on this pin, values start to jitter by +/- 1 LSB (7bit) I think that you can use the common MIOS32 driver without modifications. The metal case of the pot should be grounded, cables to J5A shouldn't be longer than 10..20 cm, and it also makes sense to add a 100 nF cap from the middle pin to ground to filter high noise jitter. Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
fairplay Posted October 16, 2010 Author Report Share Posted October 16, 2010 I think that you can use the common MIOS32 driver without modifications. The metal case of the pot should be grounded, cables to J5A shouldn't be longer than 10..20 cm, and it also makes sense to add a 100 nF cap from the middle pin to ground to filter high noise jitter. ...Thank You!!!... :thumbsup: Quote Link to comment Share on other sites More sharing options...
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