diff --git a/lib/oled_text.c b/lib/oled_text.c
new file mode 100644
index 0000000..cc2789b
--- /dev/null
+++ b/lib/oled_text.c
@@ -0,0 +1,146 @@
+/* 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 3 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 .
+ *
+ */
+/** library to show display text on SSD1306 OLED display
+ * @file
+ * @author King Kévin
+ * @date 2020
+ * @note peripherals used: I²C @ref oled_ssd1306_i2c
+ */
+/* standard libraries */
+#include // standard integer types
+#include // boolean type
+#include // string utilities
+
+/* own libraries */
+#include "global.h" // global utilities
+#include "oled_text.h" // own definitions
+#include "oled_ssd1306.h" // OLED display utilities
+#include "font.h" // font glyphs
+
+/** if the OLED display is present and setup */
+static bool oled_text_present = false;
+
+/** display pixel buffer */
+static uint8_t oled_text_display[128 * 8] = {0};
+
+/** SSD1306 OLED display I2C slave address */
+#define OLED_SSD1306_SLAVE 0x3c
+
+/** look-up table to swap the bit order in a byte
+ * @remark this is useful for the OLED screen since the top pixel is the MSb
+ */
+static const uint8_t bit_order_switch_lut[256] = { 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff, };
+
+bool oled_text_setup(void)
+{
+
+ // setup SSD1306 OLED display
+ oled_text_clear(); // clean display buffer
+ oled_text_present = oled_ssd1306_setup(OLED_SSD1306_SLAVE); // setup OLED display
+ if (oled_text_present) {
+#if DEBUG
+ oled_ssd1306_test(); // test OLED display
+#endif
+ oled_text_update(); // send display buffer
+ oled_ssd1306_on(); // switch display back on
+ };
+
+ return oled_text_present;
+}
+
+void oled_text_clear(void)
+{
+ // write all buffer to 0
+ for (uint16_t i = 0; i < LENGTH(oled_text_display); i++) {
+ oled_text_display[i] = 0;
+ }
+}
+
+void oled_text_pos(uint8_t column, uint8_t row, enum font_name font_name, const char *text)
+{
+ // sanity checks
+ if (column >= 128) {
+ return;
+ }
+ if (row >= 64) {
+ return;
+ }
+ if (font_name >= FONT_MAX) {
+ return;
+ }
+ if (NULL == text) {
+ return;
+ }
+
+ const struct font_s *font = &fonts[font_name]; // get selected font
+ while (*text && column < 128) {
+ char c = *text;
+ if (c >= ' ' && c < ' ' + FONT_GLYPH_NUMBERS) {
+ for (uint8_t i = 0; i < font->width; i++) { // draw glyph from left to right
+ uint8_t col = column + i; // calculate destination column position
+ if (col >= 128) {
+ break; // end of screen reached
+ }
+ uint16_t glyph_column = font->glyphs[font->width * (c - ' ') + i]; // get glyph column to draw
+ // draw bottom part of glyph
+ uint16_t pixel_byte_row = 128 * ((row / 8) - 0) + col;
+ uint8_t glyph_byte_row = (glyph_column << (7 - (row % 8))) >> 0;
+ glyph_byte_row = bit_order_switch_lut[glyph_byte_row];
+ oled_text_display[pixel_byte_row] |= glyph_byte_row;
+ // draw middle part of glyph
+ if (row >= 8 && font->height > 8 - (row % 8)) {
+ pixel_byte_row -= 128;
+ glyph_byte_row = (glyph_column << (7 - (row % 8))) >> 8;
+ glyph_byte_row = bit_order_switch_lut[glyph_byte_row];
+ oled_text_display[pixel_byte_row] |= glyph_byte_row;
+ }
+ // draw top part of glyph
+ if (row >= 16 && font->height > 8 + (row % 8)) {
+ pixel_byte_row -= 128;
+ glyph_byte_row = ((uint32_t)glyph_column << (7 - (row % 8))) >> 16;
+ glyph_byte_row = bit_order_switch_lut[glyph_byte_row];
+ oled_text_display[pixel_byte_row] |= glyph_byte_row;
+ }
+ }
+ }
+ text++; // go to next character
+ column += font->width+1;
+ }
+}
+
+void oled_text_line(const char* text, uint8_t line_nb)
+{
+ // verify input
+ if (NULL == text) {
+ return;
+ }
+ if (line_nb > 3) { // we only use 4 lines
+ return;
+ }
+
+ // clear line
+ for (uint16_t i = 128 * (line_nb * 2); i < 128 * (line_nb * 2 + 2); i++) {
+ oled_text_display[i] = 0;
+ }
+
+ oled_text_pos(0, 15 + 16 * line_nb, FONT_KING14, text); // draw text on the left of top line
+}
+
+void oled_text_update(void)
+{
+ if (oled_text_present) { // only do something if the display is present
+ oled_ssd1306_display(oled_text_display, LENGTH(oled_text_display)); // send current display buffer
+ }
+}
diff --git a/lib/oled_text.h b/lib/oled_text.h
new file mode 100644
index 0000000..f584c23
--- /dev/null
+++ b/lib/oled_text.h
@@ -0,0 +1,45 @@
+/* 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 3 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 .
+ *
+ */
+/** library to show display text on SSD1306 OLED display
+ * @file
+ * @author King Kévin
+ * @date 2018-2020
+ * @note peripherals used: I²C @ref oled_ssd1306_i2c
+ */
+#include "font.h"
+
+/** setup OLED display
+ * @return if OLED screen is present and responsive
+ */
+bool oled_text_setup(void);
+/** clear display buffer
+ * @note update the display to clear it
+ */
+void oled_text_clear(void);
+/** draw text in display buffer
+ * @param[in] column display column where to start drawing the text (0 is left)
+ * @param[in] row display row where to put the lower end of the characters (0 is top)
+ * @param[in] font_name name of the font to use to draw the text
+ * @param[in] text text string to draw
+ */
+void oled_text_pos(uint8_t column, uint8_t row, enum font_name font_name, const char *text);
+/** draw text on display
+ * @param[in] text text to display on top left side of screen
+ * @param[in] line_nb on which line to display the text (up to 3)
+ * @note update the display to display the text
+ */
+void oled_text_line(const char* text, uint8_t line_nb);
+/** update OLED display RAM with current display buffer */
+void oled_text_update(void);