From aa41bdc0674a2a3d34e422f4e02aec43f4362c9a Mon Sep 17 00:00:00 2001
From: Savanni D'Gerinel <savanni@luminescent-dreams.com>
Date: Sun, 17 Jul 2022 23:34:20 -0400
Subject: [PATCH] Start on the i2c prototype

---
 i2c/i2c.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 i2c/i2c.h | 39 ++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)
 create mode 100644 i2c/i2c.c
 create mode 100644 i2c/i2c.h

diff --git a/i2c/i2c.c b/i2c/i2c.c
new file mode 100644
index 0000000..ee5af6c
--- /dev/null
+++ b/i2c/i2c.c
@@ -0,0 +1,60 @@
+/*
+Copyright 2022, Savanni D'Gerinel <savanni@luminescent-dreams.com>
+
+This file is part of Savanni's AVR library.
+
+This AVR library 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 AVR library 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 AVR library. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <util/delay.h>
+#include "i2c.h"
+
+void i2c_init_host(i2c_host_t *bus, i2c_error_e *error) {
+    dio_set_direction(&bus->sda, LINE_OUT);
+    dio_set(&bus->sda, 1);
+
+    dio_set_direction(&bus->scl, LINE_OUT);
+    dio_set(&bus->scl, 1);
+}
+
+void i2c_init_client(i2c_client_t *bus, i2c_error_e *error) {
+    dio_set_direction(&bus->sda, LINE_IN);
+    dio_set_direction(&bus->scl, LINE_IN);
+}
+
+void i2c_host_write_packet(i2c_host_t *bus, uint8_t value, i2c_error_e *error) {
+    dio_set(&bus->sda, 0);
+    dio_set(&bus->scl, 0);
+
+    for (int i = 7; i >= 0; i--) {
+        dio_set(&bus->sda, value & _BV(i));
+        /*
+        if (value & _BV(i)) {
+            dio_set(&bus->sda, 1);
+        } else {
+            dio_set(&bus->sda, 0);
+        }
+        */
+        dio_set(&bus->scl, 1);
+        dio_set(&bus->scl, 0);
+    }
+
+    dio_set_direction(&bus->scl, LINE_IN);
+
+}
+
+void i2c_host_write(i2c_host_t *bus, uint8_t address, uint8_t *data, size_t length, i2c_error_e *error) {
+    if (*error) return;
+
+    i2c_host_write_packet(bus, address << 1, error);
+    if (*error != ok) return;
+
+    for (int i = 0; i < length; i++) {
+        i2c_host_write_packet(bus, data[i], error);
+        if (*error != ok) return;
+    }
+}
diff --git a/i2c/i2c.h b/i2c/i2c.h
new file mode 100644
index 0000000..520851c
--- /dev/null
+++ b/i2c/i2c.h
@@ -0,0 +1,39 @@
+/*
+Copyright 2022, Savanni D'Gerinel <savanni@luminescent-dreams.com>
+
+This file is part of Savanni's AVR library.
+
+This AVR library 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 AVR library 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 AVR library. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef __I2C_H__
+#define __I2C_H__
+
+#include <base.h>
+
+typedef enum {
+    ok,
+    nak
+} i2c_error_e;
+
+typedef struct {
+    dio_t sda;
+    dio_t clk;
+} i2c_host_t;
+
+typedef struct {
+    dio_t sda;
+    dio_t clk;
+    uint8_t addr;
+}
+
+void i2c_init_host(i2c_host_t *, i2c_error_e *);
+void i2c_init_client(i2c_client_t *, i2c_error_e *); 
+
+void i2c_host_write(i2c_host_t *, uint8_t, uint8_t, size_t, i2c_error_e);
+
+#endif