📄 da0_da3.lst
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C51 COMPILER V8.02 DA0_DA3 07/14/2008 16:53:08 PAGE 1
C51 COMPILER V8.02, COMPILATION OF MODULE DA0_DA3
OBJECT MODULE PLACED IN da0_da3.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE da0_da3.c BROWSE DEBUG OBJECTEXTEND
line level source
1 //-----------------------------------------------------------------------------
2 // F02x_ADC0_ExternalInput_Mux.c
3 //-----------------------------------------------------------------------------
4 // Copyright 2005 Silicon Laboratories, Inc.
5 // http://www.silabs.com
6 //
7 // This code example illustrates using the internal analog multiplexer to
8 // measure analog voltages on up to 8 different analog inputs. Results are
9 // printed to a PC terminal program via the UART.
10 //
11 // The inputs are sequentially scanned, beginning with input 0 (AIN0.0), up
12 // to input number <ANALOG_INPUTS>-1 (maximum ANALOG_INPUTS = 8, which will
13 // scan all analog inputs AIN0.0 - AIN0.7).
14 //
15 //
16 // ADC Settling Time Requirements, Sampling Rate:
17 // ----------------------------------------------
18 //
19 // The total sample time per intput is comprised of an input setting time
20 // (Tsettle), followed by a conversion time (Tconvert):
21 //
22 // Tsample = Tsettle + Tconvert
23 //
24 // Settling and conversion times may overlap, as the ADC holds the value once
25 // conversion begins. This code example takes advantage of this to increase
26 // the settling time above the minimum required. In other words, when
27 // converting the value from analog input Ain(n), the input mux is switched
28 // over to the next input Ain(n+1) to begin settling.
29 //
30 // |--------Settling Ain(n)--------|=Conversion Ain(n)=|
31 // |--------Settling Ain(n+1)--------|=Conversion Ain(n+1)=|
32 // |--------Settling Ain(n+2)--------|
33 // ISR: Timer 2 ^ ^ ^
34 // ISR: ADC0 ^ ^
35 //
36 // The ADC input voltage must be allowed adequate time to settle before the
37 // conversion is made. This settling depends on the external source
38 // impedance, internal mux impedance, and internal capacitance.
39 // Settling time is given by:
40 //
41 // | 2^n |
42 // Tsettle = ln | --- | * Rtotal * Csample
43 // | SA |
44 //
45 // In this application, assume a 100kohm potentiometer as the voltage divider.
46 // The expression evaluates to:
47 //
48 // | 2^12 |
49 // Tsettle = ln | ---- | * 105e3 * 10e-12 = 10.2uS
50 // | 0.25 |
51 //
52 // In addition, one must allow at least 1.5uS after changing analog mux
53 // inputs or PGA settings. The settling time in this example, then, is
54 // dictated by the large external source resistance.
55 //
C51 COMPILER V8.02 DA0_DA3 07/14/2008 16:53:08 PAGE 2
56 // The conversion is 16 periods of the SAR clock <SAR_CLK>. At 2.5 MHz,
57 // this time is 16 * 400nS = 6.4 uS.
58 //
59 //
60 // Tsample, minimum = Tsettle + Tconvert
61 // = 10.2uS + 6.4uS
62 // = 16.6 uS
63 //
64 // Timer 2 is set to change the mux input and start a conversion every 20uS.
65 //
66 // General:
67 // --------
68 //
69 // The system is clocked using the internal 24.5MHz oscillator multiplied
70 // up to 49MHz by the on-chip PLL. Results are printed to the UART from a loop
71 // with the rate set by a delay based on Timer 2. This loop periodically reads
72 // the ADC value from a global array, Result.
73 //
74 // The ADC makes repeated measurements at 20uS intervals based on Timer 2.
75 // The end of each ADC conversion initiates an interrupt which calls an
76 // averaging function. <INT_DEC> samples are averaged then the Result
77 // values updated.
78 //
79 // For each power of 4 of <INT_DEC>, you gain 1 bit of effective resolution.
80 // For example, <INT_DEC> = 256 gain you 4 bits of resolution: 4^4 = 256.
81 //
82 // The ADC input multiplexer is set for a single-ended input. The example
83 // sequentially scans through the inputs, starting at AIN0.0. <ANALOG_INPUTS>
84 // inputs are read. The amplifier is set for unity gain so a voltage range of
85 // 0 to Vref (2.43V) may be measured. Although voltages up to Vdd may be
86 // applied without damaging the device, only the range 0 to Vref may be
87 // measured by the ADC. The input is available at the 8-position board-edge
88 // connector, J20, on the C8051FX20-TB.
89 //
90 // A 100kohm potentiometer may be connected as a voltage divider between
91 // VREF and AGND as shown below:
92 //
93 // ---------
94 // |
95 // 8 o| AGND ----|
96 // o| VREF ----|<-|
97 // o| AIN0.1 | |
98 // o| | |
99 // o| --------
100 // o|
101 // o|
102 // 1 o|
103 // |
104 // ---------
105 //
106 // How To Test:
107 //
108 // 1) Download code to a 'F02x device that is connected to a UART transceiver
109 // 2) Connect serial cable from the transceiver to a PC
110 // 3) On the PC, open HyperTerminal (or any other terminal program) and connect
111 // to the COM port at <BAUDRATE> and 8-N-1
112 // 4) Connect a variable voltage source (between 0 and Vref)
113 // to AIN 0.1, or a potentiometer voltage divider as shown above.
114 // 5) HyperTerminal will print the voltages measured by the device if
115 // everything is working properly. Note that some of the analog inputs are
116 // floating and will return nonzero values.
117 //
C51 COMPILER V8.02 DA0_DA3 07/14/2008 16:53:08 PAGE 3
118 // FID: 02X000016
119 // Target: C8051F02x
120 // Tool chain: Keil C51 7.50 / Keil EVAL C51
121 // Command Line: None
122 //
123 //
124 // Release 1.0
125 // -Initial Revision (PD)
126 // -18-Jul-06
127 //
128 //-----------------------------------------------------------------------------
129 // Includes
130 //-----------------------------------------------------------------------------
131
132 #include <c8051f020.h> // SFR declarations
133 #include <stdio.h>
134
135 //-----------------------------------------------------------------------------
136 // 16-bit SFR Definitions for 'F02x
137 //-----------------------------------------------------------------------------
138
139 sfr16 ADC0 = 0xbe; // ADC0 data
140 sfr16 RCAP2 = 0xca; // Timer2 capture/reload
141 sfr16 RCAP3 = 0x92; // Timer3 capture/reload
142 sfr16 TMR2 = 0xcc; // Timer2
143 sfr16 TMR3 = 0x94; // Timer3
144
145 //-----------------------------------------------------------------------------
146 // Global Constants
147 //-----------------------------------------------------------------------------
148
149 #define BAUDRATE 115200 // Baud rate of UART in bps
150 #define SYSCLK 22118400 // Output of PLL derived from (INTCLK*2)
151 #define INT_DEC 256 // Integrate and decimate ratio
152 #define SAR_CLK 2500000 // Desired SAR clock speed
153
154 #define SAMPLE_DELAY 250 // Delay in ms before displaying sample
155
156 #define ANALOG_INPUTS 8 // Number of AIN pins to measure
157 // (min=1, max=8)
158
159 sbit LED = P1^6; // LED='1' means ON
160 sbit SW1 = P3^7; // SW1='0' means switch pressed
161
162 //-----------------------------------------------------------------------------
163 // Function Prototypes
164 //-----------------------------------------------------------------------------
165
166 void OSCILLATOR_Init (void);
167 void PORT_Init (void);
168 void UART0_Init (void);
169 void ADC0_Init (void);
170 void TIMER3_Init (void);
171 void ADC0_ISR (void);
172 void TIMER2_ISR (void);
173 void Wait_MS (unsigned int ms);
174
175 //-----------------------------------------------------------------------------
176 // Global Variables
177 //-----------------------------------------------------------------------------
178
179 long Result[ANALOG_INPUTS]; // ADC0 decimated value, one for each
C51 COMPILER V8.02 DA0_DA3 07/14/2008 16:53:08 PAGE 4
180 // analog input
181 unsigned char amux_input=0; // index of analog MUX inputs
182 unsigned char amux_convert=0;
183
184 //-----------------------------------------------------------------------------
185 // main() Routine
186 //-----------------------------------------------------------------------------
187
188 void main (void)
189 {
190 1 unsigned char i;
191 1 long measurement; // measured voltage in mV
192 1
193 1 WDTCN = 0xde; // Disable watchdog timer
194 1 WDTCN = 0xad;
195 1
196 1 OSCILLATOR_Init (); // Initialize oscillator
197 1 PORT_Init (); // Initialize crossbar and GPIO
198 1 UART0_Init (); // Initialize UART1
199 1
200 1 TIMER3_Init (); // Initialize Timer2 to overflow at 1 mS
201 1
202 1 ADC0_Init (); // Init ADC
203 1
204 1 AD0EN = 1; // Enable ADC
205 1
206 1 EA = 1; // Enable global interrupts
207 1
208 1 while (1)
209 1 {
210 2 EA = 0; // Disable interrupts
211 2
212 2 printf("\f");
213 2 for(i=0; i<ANALOG_INPUTS; i++)
214 2 {
215 3 // The 12-bit ADC value is averaged across INT_DEC measurements.
216 3 // The result is then stored in Result, and is right-justified
217 3 // The measured voltage applied to AIN 0.1 is then:
218 3 //
219 3 // Vref (mV)
220 3 // measurement (mV) = --------------- * Result (bits)
221 3 // (2^12)-1 (bits)
222 3
223 3 measurement = Result[i] * 2430 / 4095;
224 3 printf("AIN0.%bu voltage: %ld\tmV\n",i,measurement);
225 3 }
226 2 EA = 1; // Re-enable interrupts
227 2 Wait_MS(SAMPLE_DELAY); // Wait before displaying new values
228 2 }
229 1 }
230
231 //-----------------------------------------------------------------------------
232 // Initialization Subroutines
233 //-----------------------------------------------------------------------------
234
235 //-----------------------------------------------------------------------------
236 // OSCILLATOR_Init
237 //-----------------------------------------------------------------------------
238 //
239 // Return Value : None
240 // Parameters : None
241 //
C51 COMPILER V8.02 DA0_DA3 07/14/2008 16:53:08 PAGE 5
242 // This routine initializes the system clock to use an 22.1184MHz crystal
243 // as its clock source.
244 //
245 //
246 //-----------------------------------------------------------------------------
247 void OSCILLATOR_Init (void)
248 {
249 1 int i; // delay counter
250 1
251 1 OSCXCN = 0x67; // start external oscillator with
252 1 // 22.1184MHz crystal
253 1
254 1 for (i=0; i < 256; i++) ; // wait for oscillator to start
255 1
256 1 while (!(OSCXCN & 0x80)) ; // Wait for crystal osc. to settle
257 1
258 1 OSCICN = 0x88; // select external oscillator as SYSCLK
259 1 // source and enable missing clock
260 1 // detector
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