Diff: i2c.cpp

Revision:

0:d55659b0c4a0

Child:

1:8465801be23f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/i2c.cpp	Thu Nov 18 10:23:43 2010 +0000
@@ -0,0 +1,143 @@
+/**
+ * Copyright (c) 2010 Roy van Dam <roy@negative-black.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "i2c.hpp"
+
+namespace SHTx {
+	I2C::I2C(PinName sda, PinName scl) :
+	scl_pin(scl), sda_pin(sda), frequency(10) {
+		this->sda_pin.output();
+		this->scl_pin.output();
+	}
+
+	void
+	I2C::setFrequency(uint32_t hz) {
+		this->frequency = (1000000 / hz);
+	}
+
+	void
+	I2C::start(void) {
+	    this->output();
+		this->sda(1);
+		this->scl(1);
+		this->sda(0);
+		this->scl(0);
+		this->scl(1);
+		this->sda(1);
+		this->scl(0);
+	}
+
+	void
+	I2C::stop(void) {
+	    this->output();
+		this->sda(0);
+		this->scl(1);
+		this->sda(1);
+	}
+
+	bool
+	I2C::wait(void) {
+		bool ack = false;
+	
+		this->input();
+		for (uint8_t i = 0; i < 500 && !ack; i++) {
+			ack = !this->sda_pin;
+			wait_ms(1);
+		}
+	
+		return ack;
+	}
+
+	bool
+	I2C::write(uint8_t data) {
+	    bool ack;
+
+	    this->output();
+		for (uint8_t i = 8; i; i--) {
+		    this->shift_out(data & 0x80);
+		    data <<= 1;
+		}
+    
+	    this->input();
+	    ack = !this->shift_in();
+    
+		return ack;
+	}
+
+	uint8_t
+	I2C::read(bool ack) {
+		uint8_t data = 0;
+	
+	    this->input();
+		for (uint8_t i = 8; i; i--) {
+		    data <<= 1;
+			data  |= this->shift_in();
+		}
+	
+	    this->output();
+		this->shift_out(!ack);
+	
+		return data;
+	}
+
+	void
+	I2C::output(void) {
+		this->sda_pin.output();
+	}
+
+	void
+	I2C::input(void) {
+		this->sda_pin.input();
+	}
+
+	void
+	I2C::sda(bool value) {
+		this->sda_pin = value;
+		wait_us(this->frequency);
+	}
+
+	void
+	I2C::scl(bool value) {
+		this->scl_pin = value;
+		wait_us(this->frequency);
+	}
+
+	void
+	I2C::shift_out(bool bit) {
+	    this->sda(bit);
+		this->scl(1);
+		this->scl(0);
+	}
+
+	bool
+	I2C::shift_in(void) {
+	    wait_us(this->frequency);
+		this->scl(1);
+		bool bit = this->sda_pin;
+		this->scl(0);
+		return bit;
+	}
+}
\ No newline at end of file