Re: 49-key scanning issue
Verfasst: 25. Jan 2025, 14:54
You need two scan boards each one for each manual.
These scan boards MUST contain components for the maximum of
61 keys / manual even when You only use 49 keys !!!
So Keys from 50 to 61 are only not connected
BUT the IC pins of these key contacts are connected via R network 4k7 to + 5 V !!!
Thats important !!
Specially at last key 49 it is important that there has to be a pullup resistor
4K 7 to + 5 V.
At the other pins of the IUC 4014 there is always a reistor network with 8 x 4k7.
The keys are connected via resistor 10 ohm to the pins of the 4014 IC
These IC pins are connected to the described resistor network 8 x 4k7.
When a keyboard has only 49 key instead of 61 keys the not used key input pins
are connected via resistor network 8 x 4k7 to + 5 Volt
The keys switch to GND.
So when You have there many tone events at key 49 there must be not wanted
vconnection th GND.
These scan boards MUST contain components for the maximum of
61 keys / manual even when You only use 49 keys !!!
So Keys from 50 to 61 are only not connected
BUT the IC pins of these key contacts are connected via R network 4k7 to + 5 V !!!
Thats important !!
Specially at last key 49 it is important that there has to be a pullup resistor
4K 7 to + 5 V.
At the other pins of the IUC 4014 there is always a reistor network with 8 x 4k7.
The keys are connected via resistor 10 ohm to the pins of the 4014 IC
These IC pins are connected to the described resistor network 8 x 4k7.
When a keyboard has only 49 key instead of 61 keys the not used key input pins
are connected via resistor network 8 x 4k7 to + 5 Volt
The keys switch to GND.
So when You have there many tone events at key 49 there must be not wanted
vconnection th GND.