diff --git a/firmware/src/main.c b/firmware/src/main.c
index 1f5699a..40796d8 100644
--- a/firmware/src/main.c
+++ b/firmware/src/main.c
@@ -25,6 +25,10 @@
 #define SI5351_ADDRESS 0x60
 
 #define SI5351_REGISTER_3_OUTPUT_ENABLE_CONTROL 3
+// ...
+#define SI5351_REGISTER_26_MSNA 26
+#define SI5351_REGISTER_34_MSNB 34
+// ...
 #define SI5351_REGISTER_177_PLL_RESET 177
 
 #define SYM_ENTRY(SYM) { SYM, sizeof(SYM) / 2 }
@@ -165,15 +169,30 @@ static const struct symbol symbol_table[] = { SYM_ENTRY(sym_0),
 
 enum input { cw, ccw, click, hold };
 
-static volatile enum state { home, ch1, ch2, ch3, setup } current_state = home;
+static volatile enum state { home, ch1, ch2, ch3, plla, pllb, setup } current_state = home;
 static volatile enum state home_state = ch1;
 static volatile enum setup_state { contrast, backlight, back, change_contrast, change_backlight } setup_state = contrast;
+static volatile enum pll_state { integer, numerator, denominator, pll_back, change_integer, change_numerator, change_denominator } pll_state = integer;
 
 static volatile uint8_t enc = 0;
+static volatile uint8_t select_offset = 0;
+static volatile uint8_t digit_select = 0;
+static volatile uint8_t max_digits = 0;
+static volatile bool digit_selected = false;
 
 static volatile uint8_t value_contrast;
 static volatile uint8_t value_backlight;
 
+struct pll_config {
+    uint8_t reg;
+    uint32_t integer;
+    uint32_t numerator;
+    uint32_t denominator;
+};
+
+static volatile struct pll_config plla_config = { SI5351_REGISTER_26_MSNA, 0, 0, 0 };
+static volatile struct pll_config pllb_config = { SI5351_REGISTER_34_MSNB, 0, 0, 0 };
+
 static const uint8_t m_si5351_regs_15to92_149to170[100][2] = {
     // Init
     {3, 0xFF},
@@ -316,6 +335,15 @@ static const uint8_t m_si5351_regs_custom[51][2] = {
     {64, 0x00},
     {65, 0x00}};
 
+static uint32_t ten_pow(const uint8_t exponent) {
+    uint32_t result = 1;
+
+    for (uint8_t i = 0; i < exponent; i++)
+        result *= 10;
+
+    return result;
+}
+
 static void spi_init(void) {
     SPI_DDR |= (1 << SPI_SCK) | (1 << SPI_MOSI) | (1 << SPI_SS);
     SPI_PORT |= (1 << SPI_SS);
@@ -469,6 +497,51 @@ static void lcd_write_integer_page(const uint32_t integer,
     }
 }
 
+static void lcd_write_selected_integer_page(const uint32_t integer,
+                                            const uint8_t digits,
+                                            const uint8_t page,
+                                            const bool invert) {
+    max_digits = digits;
+
+    if (digits != 0 || integer != 0) {
+        uint8_t input_digits = 0;
+        uint32_t comperator = 1;
+
+        // Get digits
+        for (; comperator <= integer; comperator *= 10, input_digits++);
+        lcd_write_kerning(1, invert);
+
+        // Print leading zeroes
+        for (int8_t i = digits - input_digits; i > 0; i--) {
+            if (input_digits + i - 1 != digit_select) {
+                lcd_write_kerning(1, invert);
+                lcd_write_digit_page(0, page, invert);
+                lcd_write_kerning(1, invert);
+            } else {
+                lcd_write_kerning(1, !invert);
+                lcd_write_digit_page(0, page, !invert);
+                lcd_write_kerning(1, !invert);
+            }
+        }
+
+        // Print number itself
+        for (; comperator >= 10; comperator /= 10, input_digits--) {
+            if (input_digits - 1 != digit_select) {
+                lcd_write_kerning(1, invert);
+                lcd_write_digit_page((integer % comperator) / (comperator / 10),
+                                     page, invert);
+                lcd_write_kerning(1, invert);
+            } else {
+                lcd_write_kerning(1, !invert);
+
+                lcd_write_digit_page((integer % comperator) / (comperator / 10),
+                                     page, !invert);
+                lcd_write_kerning(1, !invert);
+            }
+        }
+    }
+}
+
 static void twi_error(bool inverted) {
     if (inverted)
         lcd_fill(0xFF);
@@ -587,6 +660,8 @@ static void draw_home(void) {
     bool ch1_selected = false;
     bool ch2_selected = false;
     bool ch3_selected = false;
+    bool plla_selected = false;
+    bool pllb_selected = false;
     bool setup_selected = false;
 
     switch (home_state) {
@@ -599,6 +674,12 @@ static void draw_home(void) {
     case ch3:
         ch3_selected = true;
         break;
+    case plla:
+        plla_selected = true;
+        break;
+    case pllb:
+        pllb_selected = true;
+        break;
     default: // setup
         setup_selected = true;
         break;
@@ -617,12 +698,144 @@ static void draw_home(void) {
         lcd_write_string_page("CH3\0", 2, i, ch3_selected);
         lcd_write_kerning(2, ch3_selected);
 
-        lcd_move_cursor(33, 6 + i);
+        lcd_move_cursor(0, 6 + i);
+        lcd_write_kerning(1, plla_selected);
+        lcd_write_string_page("PLL\0", 1, i, plla_selected);
+
+        lcd_write_string_page("A\0", 1, i, plla_selected);
+        lcd_write_kerning(2, plla_selected);
+
+        lcd_write_kerning(1, false);
+
+        lcd_write_kerning(1, pllb_selected);
+        lcd_write_string_page("PLL\0", 1, i, pllb_selected);
+
+        lcd_write_string_page("B\0", 1, i, pllb_selected);
+        lcd_write_kerning(2, pllb_selected);
+
+        lcd_move_cursor(61, 6 + i);
         lcd_write_string_page("SETUP\0", 2, i, setup_selected);
         lcd_write_kerning(2, setup_selected);
     }
 }
 
+static void draw_pll(void) {
+    lcd_fill(0x00);
+
+    volatile struct pll_config* pll_config = &plla_config;
+
+    switch (current_state) {
+    case plla:
+        pll_config = &plla_config;
+        break;
+    case pllb:
+        pll_config = &pllb_config;
+        break;
+    default:
+        break;
+    }
+
+    bool integer_selected = false;
+    bool numerator_selected = false;
+    bool denominator_selected = false;
+    bool back_selected = false;
+    bool change_integer_selected = false;
+    bool change_numerator_selected = false;
+    bool change_denominator_selected = false;
+
+    switch (pll_state) {
+    case integer:
+        integer_selected = true;
+        break;
+    case numerator:
+        numerator_selected = true;
+        break;
+    case denominator:
+        denominator_selected = true;
+        break;
+    case pll_back:
+        back_selected = true;
+        break;
+    case change_integer:
+        change_integer_selected = true;
+        break;
+    case change_numerator:
+        change_numerator_selected = true;
+        break;
+    case change_denominator:
+        change_denominator_selected = true;
+        break;
+    }
+
+    for (uint8_t i = 0; i < 2; i++) {
+        lcd_move_cursor(0, i);
+        lcd_write_kerning(33, true);
+        lcd_write_string_page("PLL\0", 2, i, true);
+        lcd_write_kerning(4, true);
+        switch (current_state) {
+        case plla:
+            lcd_write_string_page("A\0", 2, i, true);
+            break;
+        case pllb:
+            lcd_write_string_page("B\0", 2, i, true);
+            break;
+        default:
+            break;
+        }
+        lcd_write_kerning(35, true);
+    }
+
+    if (select_offset == 0)
+        for (uint8_t i = 0; i < 2; i++) {
+            lcd_move_cursor(0, 2 + i);
+            lcd_write_kerning(1, integer_selected);
+            lcd_write_string_page("INTEGER:\0", 1, i, integer_selected);
+            lcd_write_kerning(2, integer_selected);
+            lcd_write_kerning(7, false);
+            if (change_integer_selected)
+                lcd_write_selected_integer_page(pll_config->integer, 6,
+                                                i, false);
+            else
+                lcd_write_integer_page(pll_config->integer, 6, i, false);
+            lcd_write_kerning(2, false);
+        }
+
+    for (uint8_t i = 0; i < 2; i++) {
+        lcd_move_cursor(0, 4 + i - select_offset * 2);
+        lcd_write_kerning(1, numerator_selected);
+        lcd_write_string_page("NUM:\0", 1, i, numerator_selected);
+        lcd_write_kerning(2, numerator_selected);
+        lcd_write_kerning(21, false);
+        if (change_numerator_selected)
+            lcd_write_selected_integer_page(pll_config->numerator, 7,
+                                            i, false);
+        else
+            lcd_write_integer_page(pll_config->numerator, 7, i, false);
+        lcd_write_kerning(2, false);
+    }
+
+    for (uint8_t i = 0; i < 2; i++) {
+        lcd_move_cursor(0, 6 + i - select_offset * 2);
+        lcd_write_kerning(1, denominator_selected);
+        lcd_write_string_page("DENOM:\0", 1, i, denominator_selected);
+        lcd_write_kerning(2, denominator_selected);
+        lcd_write_kerning(8, false);
+        if (change_denominator_selected)
+            lcd_write_selected_integer_page(pll_config->denominator, 7,
+                                            i, false);
+        else
+            lcd_write_integer_page(pll_config->denominator, 7, i, false);
+        lcd_write_kerning(2, false);
+    }
+
+    if (select_offset == 1)
+        for (uint8_t i = 0; i < 2; i++) {
+            lcd_move_cursor(33, 6 + i);
+            lcd_write_string_page("BACK\0", 2, i, back_selected);
+            lcd_write_kerning(2, back_selected);
+        }
+}
+
 static void draw_setup(void) {
     lcd_fill(0x00);
 
@@ -687,8 +900,8 @@ static void draw_setup(void) {
 static void change_state(const enum state new_state) {
     switch (new_state) {
     case home:
-        draw_home();
         current_state = home;
+        draw_home();
         break;
     case ch1:
         break;
@@ -696,10 +909,22 @@ static void change_state(const enum state new_state) {
         break;
     case ch3:
         break;
+    case plla:
+        select_offset = 0;
+        pll_state = integer;
+        current_state = plla;
+        draw_pll();
+        break;
+    case pllb:
+        select_offset = 0;
+        pll_state = integer;
+        current_state = pllb;
+        draw_pll();
+        break;
     case setup:
         setup_state = contrast;
-        draw_setup();
         current_state = setup;
+        draw_setup();
         break;
     }
 }
@@ -726,6 +951,171 @@ static void update_home(const enum input event) {
     }
 }
 
+static void update_pll(const enum input event) {
+    volatile struct pll_config* pll_config = &plla_config;
+
+    switch (current_state) {
+    case plla:
+        pll_config = &plla_config;
+        break;
+    case pllb:
+        pll_config = &pllb_config;
+        break;
+    default:
+        break;
+    }
+
+    switch (event) {
+    case cw:
+        switch (pll_state) {
+        case integer:
+        case numerator:
+        case denominator:
+        case pll_back:
+            pll_state++;
+            if (pll_state > denominator)
+                select_offset = 1;
+            if (pll_state > pll_back) {
+                select_offset = 0;
+                pll_state = integer;
+            }
+            break;
+        case change_integer:
+            if (digit_selected)
+                pll_config->integer += ten_pow(digit_select);
+            else
+                if (--digit_select > max_digits)
+                    digit_select = max_digits - 1;
+            break;
+        case change_numerator:
+            if (digit_selected)
+                pll_config->numerator += ten_pow(digit_select);
+            else
+                if (--digit_select > max_digits)
+                    digit_select = max_digits - 1;
+            break;
+        case change_denominator:
+            if (digit_selected)
+                pll_config->denominator += ten_pow(digit_select);
+            else
+                if (--digit_select > max_digits)
+                    digit_select = max_digits - 1;
+            break;
+        }
+        draw_pll();
+        break;
+    case ccw:
+        switch (pll_state) {
+        case integer:
+        case numerator:
+        case denominator:
+        case pll_back:
+            pll_state--;
+            if (pll_state < numerator)
+                select_offset = 0;
+            if (pll_state > pll_back) {
+                select_offset = 1;
+                pll_state = pll_back;
+            }
+            break;
+        case change_integer:
+            // TODO: Fix going back to zero
+            if (digit_selected)
+                pll_config->integer -= ten_pow(digit_select);
+            else
+                if (++digit_select >= max_digits)
+                    digit_select = 0;
+            break;
+        case change_numerator:
+            // TODO: Fix going back to zero
+            if (digit_selected)
+                pll_config->numerator -= ten_pow(digit_select);
+            else
+                if (++digit_select >= max_digits)
+                    digit_select = 0;
+            break;
+        case change_denominator:
+            // TODO: Fix going back to zero
+            if (digit_selected)
+                pll_config->denominator -= ten_pow(digit_select);
+            else
+                if (++digit_select >= max_digits)
+                    digit_select = 0;
+            break;
+        }
+        draw_pll();
+        break;
+    case click:
+        switch (pll_state) {
+        case integer:
+            pll_state = change_integer;
+            draw_pll();
+            break;
+        case numerator:
+            pll_state = change_numerator;
+            draw_pll();
+            break;
+        case denominator:
+            pll_state = change_denominator;
+            draw_pll();
+            break;
+        case pll_back:
+            change_state(home);
+            break;
+        case change_integer:
+            if (digit_selected) {
+                // TODO: Save/write new value
+                digit_selected = false;
+                digit_select = 0;
+            } else
+                digit_selected = true;
+            break;
+        case change_numerator:
+            if (digit_selected) {
+                // TODO: Save/write new value
+                digit_selected = false;
+                digit_select = 0;
+            } else
+                digit_selected = true;
+            break;
+        case change_denominator:
+            if (digit_selected) {
+                // TODO: Save/write new value
+                digit_selected = false;
+                digit_select = 0;
+            } else
+                digit_selected = true;
+            break;
+        }
+        break;
+    case hold:
+        switch (pll_state) {
+        case integer:
+        case numerator:
+        case denominator:
+        case pll_back:
+            change_state(home);
+            break;
+        case change_integer:
+            digit_selected = false;
+            pll_state = integer;
+            draw_pll();
+            break;
+        case change_numerator:
+            digit_selected = false;
+            pll_state = integer;
+            draw_pll();
+            break;
+        case change_denominator:
+            digit_selected = false;
+            pll_state = integer;
+            draw_pll();
+            break;
+        }
+        break;
+    }
+}
+
 static void update_setup(const enum input event) {
     switch (event) {
     case cw:
@@ -836,6 +1226,12 @@ static void update_state(const enum input event) {
         break;
     case ch3:
         break;
+    case plla:
+        update_pll(event);
+        break;
+    case pllb:
+        update_pll(event);
+        break;
     case setup:
         update_setup(event);
         break;