TCA8418 Chip Bug????
TCA8418 seems to be a problem.
one or two keypad press is works well.
However, multiple 3, 4,5,6 keypad pressing => problem..!!!!!!!!
I was used as shown below.
1) Chip Setting (8x8 matrix)
{ REG_CFG, 0x19 }, { REG_KP_GPIO1, 0xff }, // Keypad or GPIO { REG_KP_GPIO2, 0xff }, { REG_KP_GPIO3, 0x00 }, { REG_DEBOUNCE_DIS1, 0x00 }, // Debounce Enable/Disable { REG_DEBOUNCE_DIS2, 0x00 }, { REG_DEBOUNCE_DIS3, 0x00 }, { REG_GPIO_PULL1, 0x00 }, // GPIO Pull Up Enable/Disable { REG_GPIO_PULL2, 0x00 }, { REG_GPIO_PULL3, 0x00 },
2) Test
case 1) 1 press : (R2, C0) => read value(21) is ok.
case 2) 2 press : (R2, C0) + (R1, C0) => read value (21) + read value (11) is ok...
case 3) 3 press : (R2, C0) + (R1, C0) + (R2, C3) => read value (21) + read value (11) + read value (13) + read value (23)
case 3 is fail. I pressed the threee keys, but event is 4 event.
I want to know. Does it support multiple key press???
I need your help..
thank you..
What you are seeing is the "ghost key" phenomenon that occurs when three keys that form an L shape on the matrix are pressed down. This shorts out the fourth key switch (diagonally opposite from the corner of the L), leading to the encoder seeing 4 events instead of the expected 3. You can use 1N4148s in series with the switches to suppress the "ghosting" while maintaining multi-key support.