Revision: 1896
Author: eur.van.andel
Date: Thu Apr 8 06:07:41 2010
Log: added MCP3424 18 bits, four cahnnel delta-sigma I2C AD converter
sample will follow with type K thermocouple and MCP9800 cold-juction
compensation
http://code.google.com/p/jallib/source/detail?r=1896
Added:
/trunk/include/external/adc
/trunk/include/external/adc/mcp3424.jal
=======================================
--- /dev/null
+++ /trunk/include/external/adc/mcp3424.jal Thu Apr 8 06:07:41 2010
@@ -0,0 +1,168 @@
+-- Title: mcp342, 18-bit, multi-channel delta-sigma AD converter with I2C
output
+-- Author: Eur van Andel, [email protected] Copyright (c) 2010
+-- Compiler: =2.4m
+--
+-- This file is part of jallib (http://jallib.googlecode.com)
+-- Released under the ZLIB license
(http://www.opensource.org/licenses/zlib-license.html)
+--
+-- Description: this library works with the MCP3424 AD converter from
Microchip with up to 18 bits accuracy
+-- Datasheet: DS22088B
+
+-- Declare this in main program:
+
+-- if you want to use more than one MCP3424, use the address pins:
+-- const byte mcp3424_1_addr = 0b1101_0000 -- both ADR0 and ADR1 tied to
Vss
+-- const byte mcp3424_2_addr = 0b1101_1000 -- ADR0 tied to Vdd, ADR1
tied to Vss
+-- i2c setup
+-- const word _i2c_bus_speed = 1 ; * 100kHz
+-- const bit _i2c_level = true ; i2c levels (not SMB)
+-- include i2c_hardware
+-- i2c_initialize()
+
+-- var byte i2c_tx_buffer[10]
+-- var byte i2c_rx_buffer[10]
+-- include i2c_level1 -- send_receive functions
+
+var byte config_reg
+var bit _RDY at config_reg : 7 = 1
+var bit C1 at config_reg : 6 = 0
+var bit C0 at config_reg : 5 = 0
+var bit _O at config_reg : 4 = 1
+var bit S1 at config_reg : 3 = 0
+var bit S0 at config_reg : 2 = 0
+var bit G1 at config_reg : 1 = 0
+var bit G0 at config_reg : 0 = 0
+
+
+function mcp3424_set18bits(byte in address) return bit is
+ var bit tx_ok
+ S0 = true
+ S1 = true
+ i2c_start()
+ tx_ok = i2c_transmit_byte(address)
+ tx_ok = tx_ok & i2c_transmit_byte(config_reg)
+ i2c_stop()
+ return tx_ok
+end function
+
+
+-- channel should be 1 .. 4, as per datasheet DS22088B page 18
+-- if channel = 0, 1 is assumed. If channel is > 4, 4 is assumed
+function mcp3424_set_channel(byte in address, byte in channel) return bit
is
+ var bit tx_ok
+ var bit CH0 at channel : 0
+ var bit CH1 at channel : 1
+
+ if channel > 4 then
+ channel = 4
+ elsif channel == 0 then
+ channel = 1
+ end if
+ channel = channel - 1 -- scale from 0..3
+
+ C0 = CH0
+ C1 = CH1
+ i2c_start()
+ tx_ok = i2c_transmit_byte(address)
+ tx_ok = tx_ok & i2c_transmit_byte(config_reg) -- config register
address
+ i2c_stop()
+ return tx_ok
+end function
+
+
+-- gain should be 1, 2, 4, 8, as per datasheet DS22088B page 18
+-- gain = 0,1 -> 1 / 2 -> 2, 3,4 -> 4 / 5..255 -> 8
+function mcp3424_set_gain(byte in address, byte in gain) return bit is
+ var bit tx_ok
+ if gain < 2 then
+ G0 = 0 -- gain = 1
+ G1 = 0
+ elsif gain < 3 then
+ G0 = 1 -- gain = 2
+ G1 = 0
+ elsif gain < 5 then
+ G0 = 0 -- gain = 4
+ G1 = 1
+ else
+ G0 = 1 -- gain = 8
+ G1 = 1
+ end if
+ i2c_start()
+ tx_ok = i2c_transmit_byte(address)
+ tx_ok = tx_ok & i2c_transmit_byte(config_reg) -- config register
address
+ i2c_stop()
+ return tx_ok
+end function
+
+
+function mcp3424_get_16(byte in address) return word is
+ var word temp
+ var bit tx_ok
+ tx_ok = i2c_send_receive(address, 0, 2)
+ temp = word(i2c_rx_buffer[0]) << 8 + i2c_rx_buffer[1]
+ return temp
+end function
+
+
+function mcp3424_get_18(byte in address) return sdword is
+ var sdword temp
+ var bit tx_ok
+ var bit sign at i2c_rx_buffer[0] : 1
+ tx_ok = i2c_send_receive(address, 0, 3)
+ temp = (sdword(i2c_rx_buffer[0] & 0b0000_0001) << 16) +
(sdword(i2c_rx_buffer[1]) << 8) + (i2c_rx_buffer[2])
+ if sign then
+ return -(0x02_00_00 - temp) -- 0x2_00_00 or 2^17
+ else
+ return temp
+ end if
+end function
+
+
+
+-- gain should be 1, 2, 4, 8, as per datasheet DS22088B page 18
+-- if gain = 0,1 -> 1 / 2 -> 2, 3,4 -> 4 / 5..255 -> 8
+function mcp3424_microvolt(sdword in tcvalue, byte in gain) return sdword
is
+ var bit tx_ok
+ var sdword temp
+ if gain < 2 then
+ gain = 0 -- shift values
+ elsif gain < 3 then
+ gain = 1
+ elsif gain < 5 then
+ gain = 2
+ else
+ gain = 3
+ end if
+
+ temp = tcvalue * 15625
+ temp = temp >> gain -- faster
+ temp = temp / 1000
+ return temp
+end function
+
+-- gain should be 1, 2, 4, 8, as per datasheet DS22088B page 18
+-- if gain = 0,1 -> 1 / 2 -> 2, 3,4 -> 4 / 5..255 -> 8
+function mcp3424_millivolt(sdword in tcvalue, byte in gain) return sword is
+ var bit tx_ok
+ var sdword temp
+ if gain < 2 then
+ gain = 0 -- shift values
+ elsif gain < 3 then
+ gain = 1
+ elsif gain < 5 then
+ gain = 2
+ else
+ gain = 3
+ end if
+
+ temp = tcvalue * 15625
+ temp = temp >> gain -- faster
+ temp = temp / 1_000_000
+ return sword(temp)
+end function
+
+
+
+
+
+
--
You received this message because you are subscribed to the Google Groups
"jallib" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/jallib?hl=en.
