PIC32MX: I2C DAC - Revision history

NickMarchuk: /* Overview */

2010-03-06T18:34:09Z

Overview

← Older revision		Revision as of 13:34, 6 March 2010
Line 1:		Line 1:
	== Overview ==		== Overview ==
	Note: PROJECT NOT FULLY FUNCTIONAL!

	On this page we will present code and a wiring schematic that allows for the PIC32MX to speak to an 8-bit Digital to Analog Converter. In particular, our project used the MAX518 DAC.		On this page we will present code and a wiring schematic that allows for the PIC32MX to speak to an 8-bit Digital to Analog Converter. In particular, our project used the MAX518 DAC.

		⚫	The MAX518 requires three bytes (note: 1 byte = 8 bits) of information every time it changes its output. The first byte defines the DAC as a slave, and contains the address. This byte WILL NOT change when repeatedly sending data to the DAC. The next byte is the command byte. The bits are, in order of most significant to least significant: R2, R1, R0, RST, PD, X, X, A0. R2 = R1 = R0 =0. This is always true. The next bit, RST, will reset all registers if set to 1. Setting PD to 1 will tell the device to hibernate after it outputs the desired data. The next two bits do not matter (X = don't care). Finally, the address bit, instructing the DAC which output to send the data too. The third byte sent to the MAX518 is the 8 bit value the DAC should output.
	While we were able to send data to the DAC, we were NOT able to elicit output from said DAC.

	This particular DAC, the MAX518 requires three bytes (note: 1 byte = 8 bits) of information every time it changes its output. The first byte defines the DAC as a slave, and contains the address. This byte WILL NOT change when repeatedly sending data to the DAC. The next byte is the actual data the IC should convert.

⚫	The ~~third~~ byte is ~~named~~ the command byte. The bits are, in order of most significant to least significant: R2, R1, R0, RST, PD, X, X, A0. R2 = R1 = R0 =0. This is always true. The next bit, RST, will reset all registers if set to 1. Setting PD to 1 will tell the device to hibernate after it outputs the desired data. The next two bits do not matter (X = don't care). Finally, the address bit, instructing the DAC which output to send the data too.

	== Circuit ==		== Circuit ==

NickMarchuk: /* Circuit */

2010-03-06T18:31:53Z

Circuit

← Older revision		Revision as of 13:31, 6 March 2010
Line 12:		Line 12:
	== Circuit ==		== Circuit ==

	The circuit was ~~fairly simple~~ after consulting the ~~DAC online~~ data ~~sheets~~ under the practical application wiring diagrams section~~. The Chip is a MAX 518 Digital to Analog Converter Chip~~. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).		The DAC used is a MAX518 Digital to Analog Converter Chip. The following circuit was used after consulting the MAX518 data sheet under the practical application wiring diagrams section. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).

	~~A couple~~ thing to keep in mind; the ~~DAC~~ requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V ~~as a theoretical maximum, realistically around 2.7V~~. ~~Therefore,~~ a ~~technique~~ ~~known~~ ~~as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors~~, so ~~setting the code to open drain will essentially make the output the base current~~, ~~so that when it goes high, it will saturate~~ the ~~transistor (connected~~ to ~~5V)~~ ~~sending~~ ~~5V instead of 3.3V to~~ the ~~emitter, which is connected to the DAC input~~. The ~~DAC~~ ~~inputs~~ ~~should~~ be ~~high~~ ~~when not in use,~~ and ~~although the manual says external pull-up resistors are not necessary (we used 10 kohms~~), ~~one~~ of ~~their~~ ~~example~~ ~~circuits~~ ~~had~~ ~~them, and our circuit only functioned when they were in~~ ~~place~~.		One thing to keep in mind: the MAX518 is a 5V chip and requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V. Pull up resistors R1 and R2, 1 kOhm, allow the MAX518 to receive data from the PIC. The MAX518 can change its outputs (0 and 1) from 0 to 5V with 8 bit resolution.

	[[Image:I2C Schematic.jpg]]		[[Image:I2C Schematic.jpg]]

NickMarchuk: /* Code */

2010-03-06T18:26:54Z

Code

@@ Line 19: / Line 19: @@
 == Code ==
 <pre>
@@ Line 26: / Line 25: @@
 #include <HardwareProfile_NU32.h>
 #include <plib.h>
 // Configuration Bit settings
@@ Line 35: / Line 33: @@
 // Other options are don't care
 //
-#pragma config FPLLMUL = MUL_20, FPLLIDIV = DIV_2, FPLLODIV = DIV_1, FWDTEN = OFF
+//#pragma config FPLLMUL = MUL_20, FPLLIDIV = DIV_2, FPLLODIV = DIV_1, FWDTEN = OFF
-#pragma config POSCMOD = HS, FNOSC = PRIPLL, FPBDIV = DIV_2
+//#pragma config POSCMOD = HS, FNOSC = PRIPLL, FPBDIV = DIV_2
-#define SYSCLK	(80000000) // set system clock to 80MHz
+#define I2CBAUD 100000 // 100 kHz clock
 int main(void)
+{
-	IdleI2C1();
+        IdleI2C1(); // Wait to complete
 </pre>

NickMarchuk at 20:16, 1 March 2010

2010-03-01T20:16:34Z

← Older revision		Revision as of 15:16, 1 March 2010
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	== Original Assignment ==

	'''Do not erase this section!'''

	Your assignment is to interface to the MAX518 I2C digital to analog converter (DAC).

	== Overview ==		== Overview ==
	Note: PROJECT NOT FULLY FUNCTIONAL!		Note: PROJECT NOT FULLY FUNCTIONAL!

MatthewLuther: /* Circuit */

2010-02-16T16:44:14Z

Circuit

← Older revision		Revision as of 11:44, 16 February 2010
Line 20:		Line 20:
	The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).		The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).

	A couple thing to keep in mind; the DAC requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V as a theoretical maximum, realistically around 2.7V. Therefore, a technique known as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors, so setting the code to open drain will essentially make the output the base current, so that when it goes high, it will saturate the transistor (connected to 5V) sending 5V instead of 3.3V to the emitter, which is connected to the DAC input. The DAC inputs should be high when not in use, and although the manual says external pull-up resistors are not necessary, one of their example circuits had them, and our circuit only functioned when they were in place.		A couple thing to keep in mind; the DAC requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V as a theoretical maximum, realistically around 2.7V. Therefore, a technique known as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors, so setting the code to open drain will essentially make the output the base current, so that when it goes high, it will saturate the transistor (connected to 5V) sending 5V instead of 3.3V to the emitter, which is connected to the DAC input. The DAC inputs should be high when not in use, and although the manual says external pull-up resistors are not necessary (we used 10 kohms), one of their example circuits had them, and our circuit only functioned when they were in place.

	[[Image:I2C Schematic.jpg]]		[[Image:I2C Schematic.jpg]]

GabrielHaack: /* Circuit */

2010-02-16T16:39:51Z

Circuit

← Older revision		Revision as of 11:39, 16 February 2010
Line 20:		Line 20:
	The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).		The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).

	A couple thing to keep in mind; the DAC requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V as a theoretical maximum, realistically around 2.7V. Therefore, a technique known as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors, so setting the code to open drain will essentially make the output the base current, so that when it goes high, it will saturate the transistor (connected to 5V) sending 5V instead of 3.3V to the emitter, which is connected to the DAC input.		A couple thing to keep in mind; the DAC requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V as a theoretical maximum, realistically around 2.7V. Therefore, a technique known as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors, so setting the code to open drain will essentially make the output the base current, so that when it goes high, it will saturate the transistor (connected to 5V) sending 5V instead of 3.3V to the emitter, which is connected to the DAC input. The DAC inputs should be high when not in use, and although the manual says external pull-up resistors are not necessary, one of their example circuits had them, and our circuit only functioned when they were in place.

	[[Image:I2C Schematic.jpg]]		[[Image:I2C Schematic.jpg]]

GabrielHaack: /* Circuit */

2010-02-16T15:42:45Z

Circuit

← Older revision		Revision as of 10:42, 16 February 2010
Line 19:		Line 19:

	The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).		The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).

			A couple thing to keep in mind; the DAC requires 3.5V to read 'high' at any of its inputs, and the PIC can only put out 3.3V as a theoretical maximum, realistically around 2.7V. Therefore, a technique known as open drain was used to give the PIC outputs 5V. The PIC has built-in transistors, so setting the code to open drain will essentially make the output the base current, so that when it goes high, it will saturate the transistor (connected to 5V) sending 5V instead of 3.3V to the emitter, which is connected to the DAC input.

	[[Image:I2C Schematic.jpg]]		[[Image:I2C Schematic.jpg]]

KrystianZimowski: /* Circuit */

2010-02-16T07:43:24Z

Circuit

← Older revision		Revision as of 02:43, 16 February 2010
Line 18:		Line 18:
	== Circuit ==		== Circuit ==

	The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).		The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The Chip is a MAX 518 Digital to Analog Converter Chip. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).
	[[Image:I2C Schematic.jpg]]		[[Image:I2C Schematic.jpg]]

KrystianZimowski: /* Circuit */

2010-02-16T07:41:37Z

Circuit

← Older revision		Revision as of 02:41, 16 February 2010
Line 18:		Line 18:
	== Circuit ==		== Circuit ==

			The circuit was fairly simple after consulting the DAC online data sheets under the practical application wiring diagrams section. The two PIC32 NU32 outputs are shown as Serial Data Clock (A14) and Serial Data Output (A15).
	Include a schematic and give any part numbers. A photo of your circuit is OK, but not as a replacement for a schematic.
			[[Image:I2C Schematic.jpg]]

	== Code ==		== Code ==

MatthewLuther: /* Overview */

2010-02-16T03:14:22Z

Overview

← Older revision		Revision as of 22:14, 15 February 2010
Line 12:		Line 12:
	While we were able to send data to the DAC, we were NOT able to elicit output from said DAC.		While we were able to send data to the DAC, we were NOT able to elicit output from said DAC.

	This particular DAC, the MAX518 requires three bytes (note: 1 byte = 8 bits) of information every time it changes its output. The first byte defines the DAC as a slave, and contains the address. This byte WILL NOT change when repeatedly sending data to the DAC. The next byte is the actual data the IC should convert. The third byte is named the command byte. The bits are, in order of most significant to least significant: R2, R1, R0, RST, PD, X, X, A0. R2 = R1 = R0 =0. This is always true. The next bit, RST, will reset all registers if set to 1. Setting PD to 1 will tell the device to hibernate after it outputs the desired data. The next two bits do not matter (X = don't care). Finally, the address bit, instructing the DAC which output to send the data too.		This particular DAC, the MAX518 requires three bytes (note: 1 byte = 8 bits) of information every time it changes its output. The first byte defines the DAC as a slave, and contains the address. This byte WILL NOT change when repeatedly sending data to the DAC. The next byte is the actual data the IC should convert.

			The third byte is named the command byte. The bits are, in order of most significant to least significant: R2, R1, R0, RST, PD, X, X, A0. R2 = R1 = R0 =0. This is always true. The next bit, RST, will reset all registers if set to 1. Setting PD to 1 will tell the device to hibernate after it outputs the desired data. The next two bits do not matter (X = don't care). Finally, the address bit, instructing the DAC which output to send the data too.

	== Circuit ==		== Circuit ==