/* 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 #include "keyboard.h" // Public Ion::Keyboard methods namespace Ion { namespace Keyboard { State scan() { uint64_t state = 0; for (uint8_t i=0; isetBitRange(9, 0, rowState); // TODO: 100 us seems to work, but wasn't really calculated usleep(100); // TODO: Assert pin numbers are sequentials and dynamically find 8 and 0 uint8_t column = 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 column) to state. */ state = (state << 6) | (~column & 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; isetMode(pin, GPIO::MODER::Mode::Output); RowGPIO.OTYPER()->setType(pin, GPIO::OTYPER::Type::OpenDrain); } for (uint8_t i=0; isetMode(pin, GPIO::MODER::Mode::Input); ColumnGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::Up); } } void shutdown() { for (uint8_t i=0; isetMode(pin, GPIO::MODER::Mode::Analog); RowGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::None); } for (uint8_t i=0; isetMode(pin, GPIO::MODER::Mode::Analog); ColumnGPIO.PUPDR()->setPull(pin, GPIO::PUPDR::Pull::None); } } } } }