John Kemp / mcp3208

A library to interface to the MCP3208 SPI-based ADC from Microchip. This chip provides eight analogue inputs, providing converted 12-bit values via SPI.

Dependents:   Nucleo_MCP3208_Test Nucleo_MCP3208_Ticker_Test BBMv2_eps ref_BBMv2_eps ... more

Diff: mcp3208.cpp

Revision:
0:d37e8cb188c1
Child:
1:316f86115221
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mcp3208.cpp	Mon May 23 22:58:59 2011 +0000
@@ -0,0 +1,36 @@
+#include "mcp3208.h"
+
+
+#define START_BIT   0x04
+#define MODE_SINGLE 0x02    // Single-ended mode
+#define MODE_DIFF   0x00    // Differential mode
+
+
+MCP3208::MCP3208(SPI bus, PinName cs)
+    : m_cs(cs), m_bus(bus)
+{}
+
+MCP3208::~MCP3208() {}
+
+
+void MCP3208::select() {m_cs = 0;}
+void MCP3208::deselect() {m_cs = 1;}
+
+
+int MCP3208::read_input(int channel)
+{
+    int high_byte, low_byte;
+
+    select();
+    
+    // Odd writing requirements, see the datasheet for details
+    m_bus.write(START_BIT | MODE_SINGLE | (channel >> 2));
+    high_byte = m_bus.write(channel << 6) & 0x0F;
+    low_byte = m_bus.write(0);
+    
+    deselect();
+    
+    int conv_result = (high_byte << 8) | low_byte;
+    
+    return float(conv_result) / 4096;
+}