1 files changed, 100 insertions, 0 deletions
diff --git a/src/lpc176x/i2c.c b/src/lpc176x/i2c.c
new file mode 100644
index 00000000..76c5b738
--- /dev/null
+++ b/src/lpc176x/i2c.c
@@ -0,0 +1,100 @@
+// I2C functions on lpc176x
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "LPC17xx.h" // LPC_I2C1
+#include "board/misc.h" // timer_is_before
+#include "command.h" // DECL_COMMAND
+#include "internal.h" // gpio_peripheral
+#include "sched.h" // sched_shutdown
+
+// i2c connection status flags
+enum {
+    IF_START = 1<<5, IF_STOP = 1<<4, IF_IRQ = 1<<3, IF_ACK = 1<<2, IF_ENA = 1<<6
+};
+
+static void
+i2c_init(void)
+{
+    static int have_run_init;
+    if (have_run_init)
+        return;
+    have_run_init = 1;
+
+    // Init i2c bus 1 pins
+    gpio_peripheral(0, 0, 3, 0);
+    gpio_peripheral(0, 1, 3, 0);
+
+    // Set 100Khz frequency
+    uint32_t PCLK = SystemCoreClock / 4, pulse = PCLK / (100000 * 2);
+    LPC_I2C1->I2SCLL = pulse;
+    LPC_I2C1->I2SCLH = pulse;
+
+    // Enable interface
+    LPC_I2C1->I2CONCLR = IF_START | IF_IRQ | IF_ACK | IF_ENA;
+    LPC_I2C1->I2CONSET = IF_ENA;
+}
+
+static void
+i2c_wait(uint32_t bit, uint32_t timeout)
+{
+    for (;;) {
+        uint32_t flags = LPC_I2C1->I2CONSET;
+        if (flags & bit)
+            break;
+        if (!timer_is_before(timer_read_time(), timeout))
+            shutdown("i2c timeout");
+    }
+}
+
+static void
+i2c_start(uint32_t timeout)
+{
+    LPC_I2C1->I2CONCLR = IF_ACK | IF_IRQ | IF_START;
+    LPC_I2C1->I2CONSET = IF_ACK | IF_START;
+    i2c_wait(IF_IRQ, timeout);
+    uint32_t status = LPC_I2C1->I2STAT;
+    if (status != 0x10 && status != 0x08)
+        shutdown("Failed to send i2c start");
+    LPC_I2C1->I2CONCLR = IF_START;
+}
+
+static uint32_t
+i2c_send_byte(uint8_t b, uint32_t timeout)
+{
+    LPC_I2C1->I2DAT = b;
+    LPC_I2C1->I2CONCLR = IF_IRQ;
+    i2c_wait(IF_IRQ, timeout);
+    return LPC_I2C1->I2STAT;
+}
+
+static void
+i2c_stop(uint32_t timeout)
+{
+    LPC_I2C1->I2CONSET = IF_STOP;
+    LPC_I2C1->I2CONCLR = IF_IRQ;
+    i2c_wait(IF_STOP, timeout);
+}
+
+static void
+i2c_send(uint8_t *data, int data_len)
+{
+    i2c_init();
+    uint32_t timeout = timer_read_time() + timer_from_us(5000);
+
+    i2c_start(timeout);
+    while (data_len--)
+        i2c_send_byte(*data++, timeout);
+    i2c_stop(timeout);
+}
+
+// This provides just enough functionality to program an MCP4451 chip
+void
+command_i2c_send(uint32_t *args)
+{
+    uint8_t data_len = args[0], *data = (void*)(size_t)args[1];
+    i2c_send(data, data_len);
+}
+DECL_COMMAND(command_i2c_send, "i2c_send data=%*s");