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diff --git a/keyboards/ingrained/matrix.c b/keyboards/ingrained/matrix.c
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+/*
+Copyright 2013 Oleg Kostyuk <cub.uanic@gmail.com>
+          2020 Pierre Chevalier <pierrechevalier83@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ * This code was heavily inspired by the ergodox_ez keymap, and modernized
+ * to take advantage of the quantum.h microcontroller agnostics gpio control
+ * abstractions and use the macros defined in config.h for the wiring as opposed
+ * to repeating that information all over the place.
+ */
+
+#include QMK_KEYBOARD_H
+#include "i2c_master.h"
+
+extern i2c_status_t mcp23017_status;
+#define I2C_TIMEOUT 1000
+
+// For a better understanding of the i2c protocol, this is a good read:
+// https://www.robot-electronics.co.uk/i2c-tutorial
+
+// I2C address:
+// See the datasheet, section 3.3.1 on addressing I2C devices and figure 3-6 for an
+// illustration
+// http://ww1.microchip.com/downloads/en/devicedoc/20001952c.pdf
+// All address pins of the mcp23017 are connected to the ground on the ferris
+// | 0  | 1  | 0  | 0  | A2 | A1 | A0 |
+// | 0  | 1  | 0  | 0  | 0  | 0  | 0  |
+#define I2C_ADDR 0b0100000
+#define I2C_ADDR_WRITE ((I2C_ADDR << 1) | I2C_WRITE)
+#define I2C_ADDR_READ ((I2C_ADDR << 1) | I2C_READ)
+
+// Register addresses
+// See https://github.com/adafruit/Adafruit-MCP23017-Arduino-Library/blob/master/Adafruit_MCP23017.h
+#define IODIRA 0x00  // i/o direction register
+#define IODIRB 0x01
+#define GPPUA 0x0C  // GPIO pull-up resistor register
+#define GPPUB 0x0D
+#define GPIOA 0x12  // general purpose i/o port register (write modifies OLAT)
+#define GPIOB 0x13
+#define OLATA 0x14  // output latch register
+#define OLATB 0x15
+
+bool         i2c_initialized = 0;
+i2c_status_t mcp23017_status = I2C_ADDR;
+
+uint8_t init_mcp23017(void) {
+    print("starting init");
+    mcp23017_status = I2C_ADDR;
+
+    // I2C subsystem
+    if (i2c_initialized == 0) {
+        i2c_init();  // on pins D(1,0)
+        i2c_initialized = true;
+        wait_ms(I2C_TIMEOUT);
+    }
+
+    // set pin direction
+    // - unused  : input  : 1
+    // - input   : input  : 1
+    // - driving : output : 0
+    // This means: we will read all the bits on GPIOA
+    // This means: we will write to the pins 0-4 on GPIOB (in select_rows)
+    uint8_t buf[]   = {IODIRA, 0b11111111, 0b11110000};
+    mcp23017_status = i2c_transmit(I2C_ADDR_WRITE, buf, sizeof(buf), I2C_TIMEOUT);
+    if (!mcp23017_status) {
+        // set pull-up
+        // - unused  : on  : 1
+        // - input   : on  : 1
+        // - driving : off : 0
+        // This means: we will read all the bits on GPIOA
+        // This means: we will write to the pins 0-4 on GPIOB (in select_rows)
+        uint8_t pullup_buf[] = {GPPUA, 0b11111111, 0b11110000};
+        mcp23017_status      = i2c_transmit(I2C_ADDR_WRITE, pullup_buf, sizeof(pullup_buf), I2C_TIMEOUT);
+    }
+    return mcp23017_status;
+}
+
+/* matrix state(1:on, 0:off) */
+static matrix_row_t matrix[MATRIX_ROWS];  // debounced values
+
+static matrix_row_t read_cols(uint8_t row);
+static void         init_cols(void);
+static void         unselect_rows(void);
+static void         select_row(uint8_t row);
+
+static uint8_t mcp23017_reset_loop;
+
+void matrix_init_custom(void) {
+    // initialize row and col
+
+    mcp23017_status = init_mcp23017();
+
+    unselect_rows();
+    init_cols();
+
+    // initialize matrix state: all keys off
+    for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
+        matrix[i] = 0;
+    }
+}
+
+void matrix_power_up(void) {
+    mcp23017_status = init_mcp23017();
+
+    unselect_rows();
+    init_cols();
+
+    // initialize matrix state: all keys off
+    for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
+        matrix[i] = 0;
+    }
+}
+
+// Reads and stores a row, returning
+// whether a change occurred.
+static inline bool store_matrix_row(matrix_row_t current_matrix[], uint8_t index) {
+    matrix_row_t temp = read_cols(index);
+    if (current_matrix[index] != temp) {
+        current_matrix[index] = temp;
+        return true;
+    }
+    return false;
+}
+
+bool matrix_scan_custom(matrix_row_t current_matrix[]) {
+    if (mcp23017_status) {  // if there was an error
+        if (++mcp23017_reset_loop == 0) {
+            // if (++mcp23017_reset_loop >= 1300) {
+            // since mcp23017_reset_loop is 8 bit - we'll try to reset once in 255 matrix scans
+            // this will be approx bit more frequent than once per second
+            dprint("trying to reset mcp23017\n");
+            mcp23017_status = init_mcp23017();
+            if (mcp23017_status) {
+                dprint("right side not responding\n");
+            } else {
+                dprint("right side attached\n");
+            }
+        }
+    }
+
+    bool changed = false;
+    for (uint8_t i = 0; i < MATRIX_ROWS_PER_SIDE; i++) {
+        // select rows from left and right hands
+        uint8_t left_index  = i;
+        uint8_t right_index = i + MATRIX_ROWS_PER_SIDE;
+        select_row(left_index);
+        select_row(right_index);
+
+        // we don't need a 30us delay anymore, because selecting a
+        // left-hand row requires more than 30us for i2c.
+
+        changed |= store_matrix_row(current_matrix, left_index);
+        changed |= store_matrix_row(current_matrix, right_index);
+
+        unselect_rows();
+    }
+
+    return changed;
+}
+
+static void init_cols(void) {
+    // init on mcp23017
+    // not needed, already done as part of init_mcp23017()
+
+    // init on mcu
+    pin_t matrix_col_pins_mcu[MATRIX_COLS_PER_SIDE] = MATRIX_COL_PINS_MCU;
+    for (int pin_index = 0; pin_index < MATRIX_COLS_PER_SIDE; pin_index++) {
+        pin_t pin = matrix_col_pins_mcu[pin_index];
+        setPinInput(pin);
+        writePinHigh(pin);
+    }
+}
+
+static matrix_row_t read_cols(uint8_t row) {
+    if (row < MATRIX_ROWS_PER_SIDE) {
+        pin_t        matrix_col_pins_mcu[MATRIX_COLS_PER_SIDE] = MATRIX_COL_PINS_MCU;
+        matrix_row_t current_row_value                         = 0;
+        // For each col...
+        for (uint8_t col_index = 0; col_index < MATRIX_COLS_PER_SIDE; col_index++) {
+            // Select the col pin to read (active low)
+            uint8_t pin_state = readPin(matrix_col_pins_mcu[col_index]);
+
+            // Populate the matrix row with the state of the col pin
+            current_row_value |= pin_state ? 0 : (MATRIX_ROW_SHIFTER << col_index);
+        }
+        return current_row_value;
+    } else {
+        if (mcp23017_status) {  // if there was an error
+            return 0;
+        } else {
+            uint8_t buf[]   = {GPIOA};
+            mcp23017_status = i2c_transmit(I2C_ADDR_WRITE, buf, sizeof(buf), I2C_TIMEOUT);
+            // We read all the pins on GPIOA.
+            // The initial state was all ones and any depressed key at a given column for the currently selected row will have its bit flipped to zero.
+            // The return value is a row as represented in the generic matrix code were the rightmost bits represent the lower columns and zeroes represent non-depressed keys while ones represent depressed keys.
+            // Since the pins connected to eact columns are sequential, and counting from zero up (col 5 -> GPIOA0, col 6 -> GPIOA1 and so on), the only transformation needed is a bitwise not to swap all zeroes and ones.
+            uint8_t data[] = {0};
+            if (!mcp23017_status) {
+                mcp23017_status = i2c_receive(I2C_ADDR_READ, data, sizeof(data), I2C_TIMEOUT);
+                data[0]         = ~(data[0]);
+            }
+            return data[0];
+        }
+    }
+}
+
+static void unselect_rows(void) {
+    // no need to unselect on mcp23017, because the select step sets all
+    // the other row bits high, and it's not changing to a different
+    // direction
+
+    // unselect rows on microcontroller
+    pin_t matrix_row_pins_mcu[MATRIX_ROWS_PER_SIDE] = MATRIX_ROW_PINS_MCU;
+    for (int pin_index = 0; pin_index < MATRIX_ROWS_PER_SIDE; pin_index++) {
+        pin_t pin = matrix_row_pins_mcu[pin_index];
+        setPinInput(pin);
+        writePinLow(pin);
+    }
+}
+
+static void select_row(uint8_t row) {
+    if (row < MATRIX_ROWS_PER_SIDE) {
+        // select on atmega32u4
+        pin_t matrix_row_pins_mcu[MATRIX_ROWS_PER_SIDE] = MATRIX_ROW_PINS_MCU;
+        pin_t pin                                       = matrix_row_pins_mcu[row];
+        setPinOutput(pin);
+        writePinLow(pin);
+    } else {
+        // select on mcp23017
+        if (mcp23017_status) {  // if there was an error
+                                // do nothing
+        } else {
+            // Select the desired row by writing a byte for the entire GPIOB bus where only the bit representing the row we want to select is a zero (write instruction) and every other bit is a one.
+            // Note that the row - MATRIX_ROWS_PER_SIDE reflects the fact that being on the right hand, the columns are numbered from MATRIX_ROWS_PER_SIDE to MATRIX_ROWS, but the pins we want to write to are indexed from zero up on the GPIOB bus.
+            uint8_t buf[]   = {GPIOB, 0xFF & ~(1 << (row - MATRIX_ROWS_PER_SIDE))};
+            mcp23017_status = i2c_transmit(I2C_ADDR_WRITE, buf, sizeof(buf), I2C_TIMEOUT);
+        }
+    }
+}