keyboard.cpp
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/* Keyboard initialization code
*
* The job of this code is to implement the "ion_key_state" function.
*
* The keyboard is a matrix that is laid out as follow:
*
* | PC0 | PC1 | PC2 | PC3 | PC4 | PC5 |
* -----+------+------+------+------+------+------+
* PE0 | K_A1 | K_A2 | K_A3 | K_A4 | K_A5 | K_A6 |
* -----+------+------+------+------+------+------+
* PE1 | K_B1 | K_B2 | | | | |
* -----+------+------+------+------+------+------+
* PE2 | K_C1 | K_C2 | K_C3 | K_C4 | K_C5 | K_C6 |
* -----+------+------+------+------+------+------+
* PE3 | K_D1 | K_D2 | K_D3 | K_D4 | K_D5 | K_D6 |
* -----+------+------+------+------+------+------+
* PE4 | K_E1 | K_E2 | K_E3 | K_E4 | K_E5 | K_E6 |
* -----+------+------+------+------+------+------+
* PE5 | K_F1 | K_F2 | K_F3 | K_F4 | K_F5 | |
* -----+------+------+------+------+------+------+
* PE6 | K_G1 | K_G2 | K_G3 | K_G4 | K_G5 | |
* -----+------+------+------+------+------+------+
* PE7 | K_H1 | K_H2 | K_H3 | K_H4 | K_H5 | |
* -----+------+------+------+------+------+------+
* PE8 | K_I1 | K_I2 | K_I3 | K_I4 | K_I5 | |
* -----+------+------+------+------+------+------|
*
* We decide to drive the rows (PE0-8) and read the columns (PC0-5).
*
* To avoid short-circuits, the pins E0-E8 will not be standard outputs but
* only open-drain. Open drain means the pin is either driven low or left
* floating.
* When a user presses multiple keys, a connection between two rows can happen.
* If we don't use open drain outputs, this situation could trigger a short
* circuit between an output driving high and another driving low.
*
* If the outputs are open-drain, this means that the input must be pulled up.
* So if the input reads "1", this means the key is in fact *not* pressed, and
* if it reads "0" it means that there's a short to an open-drain output. Which
* means the corresponding key is pressed.
*/
#include "keyboard.h"
// Public Ion::Keyboard methods
namespace Ion {
namespace Keyboard {
State scan() {
uint64_t state = 0;
for (uint8_t i=0; i<Device::numberOfRows; i++) {
Device::activateRow(Device::numberOfRows-1-i);
// TODO: Assert pin numbers are sequentials and dynamically find 8 and 0
uint8_t columns = Device::ColumnGPIO.IDR()->getBitRange(5,0);
/* The key is down if the input is brought low by the output. In other
* words, we want to return true if the input is low (false). So we need to
* append 6 bits of (not columns) to state. */
state = (state << 6) | (~columns & 0x3F);
}
/* Last but not least, keys number 8, 9, 10, 11, 35, 41, 47 and 53 are not
* defined. Therefore we want to make sure those bits are forced to zero in
* whatever value we return. */
state = state & 0x1F7DF7FFFFF0FF;
return State(state);
}
}
}
// Private Ion::Keyboard::Device methods
namespace Ion {
namespace Keyboard {
namespace Device {
void init() {
for (uint8_t i=0; i<numberOfRows; i++) {
uint8_t pin = RowPins[i];
RowGPIO.MODER()->setMode(pin, GPIO::MODER::Mode::Output);
RowGPIO.OTYPER()->setType(pin, GPIO::OTYPER::Type::OpenDrain);
}
for (uint8_t i=0; i<numberOfColumns; i++) {
uint8_t pin = ColumnPins[i];
ColumnGPIO.MODER()->setMode(pin, GPIO::MODER::Mode::Input);
ColumnGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::Up);
}
}
void shutdown() {
for (uint8_t i=0; i<numberOfRows; i++) {
uint8_t pin = RowPins[i];
RowGPIO.MODER()->setMode(pin, GPIO::MODER::Mode::Analog);
RowGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::None);
}
for (uint8_t i=0; i<numberOfColumns; i++) {
uint8_t pin = ColumnPins[i];
ColumnGPIO.MODER()->setMode(pin, GPIO::MODER::Mode::Analog);
ColumnGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::None);
}
}
}
}
}