=FFW=> Posted July 20, 2015 Report Share Posted July 20, 2015 hi forum, as the stm32f4 board landed in my seqv4 it is put to use using the QUAD_IIC module connected to J4A as well. BUT i get serious dropouts hwne using the ports on the QUAD_IIC. is that a known bug or error - or is it me :-) ? cheers and thanks Quote Link to comment Share on other sites More sharing options...
TK. Posted July 20, 2015 Report Share Posted July 20, 2015 I'm not aware of this - maybe the MIDI load is too high on each port, and the I2C peripheral of STM32F4 can't handle the throughput anymore? Does this only happen under high load, resp. does the problem disappear if you change certain tracks to other MIDI ports? Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
=FFW=> Posted July 21, 2015 Author Report Share Posted July 21, 2015 hey thorsten, the problem can be narrowed down to the stm32f4 core board. projects that were no problem for the lpc1769 core board now have serious dropouts on all quad_iic ports. could it maybe be a power related issue? because theres much pcbs connected (blm (by ilmenator) / tpd (by ilmenator)) which drain much power. becuase yesterday, by accident, i found that the dropouts vanished when i disconnected one of the lcd´s (whichever of the two)... thank you for looking into this issue! daniel Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 21, 2015 Report Share Posted July 21, 2015 Are you using USB power? Can you monitor the appropriate supply voltages? Quote Link to comment Share on other sites More sharing options...
=FFW=> Posted July 22, 2015 Author Report Share Posted July 22, 2015 hey latigid on, thanks for chiming in :-) and: yes - usb power is used no, i cant monitor the supply voltage... however, after trial and error checking yesterday im now sure that it must be a power related issue. because disconnecting a lcd is (consistently) preventing dropouts. im asking myself if the stm32f4 is more prone to power instabilities than the lpc1769. or if the stm32f4 is using more power itself? how to stabilise the power provided by the usb port? i tried usb hubs / and direct connection to a computer-usb-port. problem persits - no matter what type of usb port im using. i want to avoid using an external power supply! cheers Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 22, 2015 Report Share Posted July 22, 2015 With a scope or multimeter you can see if the power rails stay stable. You can also measure current levels and compare the difference between your LPC17 and STM32 cores. Note that the LPC17 has 780X regulators which should be good for 0.5A without heatsinks. How is the +5V regulated on the STM32F4 board? Quote Link to comment Share on other sites More sharing options...
=FFW=> Posted July 23, 2015 Author Report Share Posted July 23, 2015 (edited) hey latigid, an easy solution to the problem came up. i just shortened the usb-cable the stm32f4 is connected with. that worked. so the problem is, at my side, gone for now. still - the stability of the quad_iic board is prone to irregularities within the powersupply. i did not investigate the excact conditions nor the technical aspects of the power regulation on this board. so, this is for everyone having problems in this regard: - look after power issues when having dropouts using the quad_iic board with the stm32f4 core - and thank you for your help, thorsten and latigid, greatly apprechiated! cheers Edited July 23, 2015 by =FFW=> Quote Link to comment Share on other sites More sharing options...
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