M16C/26 M30262 M16C/60 REU05B0031-0100Z ADTRG/P15 M16C/20/60 MSV30262-SKP - Datasheet Archive

 

M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 1.0 Abstract The following document outlines the steps necessary to setup

 

APPLICATION NOTE M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 1.0 Abstract The following document outlines the steps necessary to setup and perform analog to digital conversions of the M16C/26 M16C/26 using repeat sweep mode 1. The ADC is useful in measuring output voltages of sensors such as accelerometers or other analog instrumentation and converting them to digital values. 2.0 Introduction The Renesas M30262 M30262 is a 16-bit MCU based on the M16C/60 M16C/60 series CPU core. The MCU features include up to 64K bytes of Flash ROM, 2K bytes of RAM, and 4K bytes of Virtual EEPROM. The peripheral set includes UARTS, Timers, DMA, and GPIO. The M16C/26 M16C/26 features an on-chip analog to digital converter (ADC). The ADC consists of one 10-bit successive approximation circuit with an ac-coupled amplifier. There are eight analog input pins, selectable conversion clock speeds, sample and hold function, and several conversion modes. Table 1 shows the performance of the ADC and Figure 1 shows a diagram of the ADC block. Table 1 ADC Performance Item Performance Method of A-D Conversion Successive approximation (capacitive coupling amplifier) Analog input voltage 0V to AVcc (Vcc) Operating clock fAD fAD, fAD2, fAD3, fAD4, fAD6, or fAD6 or fAD12 where fAD=f(Xin) Resolution 8-bit or 10-bit (selectable) Operating modes One-shot mode, repeat, single sweep mode, repeat mode, repeat sweep mode 0 and repeat sweep mode 1. Analog input pins 8 pins AN0 to AN7 A-D conversion start condition Software trigger: A-D conversion starts when the A-D conversion start flag changes to "1" Conversion speed per pin Without sample and hold function 8-bit resolution: 49 fAD cycles, 10-bit resolution: 59 fAD cycles. With sample and hold function 8-bit resolution: 28 fAD cycles, 10-bit resolution:33 fAD cycles. REU05B0031-0100Z REU05B0031-0100Z External trigger (can be retriggered): A-D conversion starts when the A-D conversion start flag is "1" and the ADTRG/P15 ADTRG/P15 input (shared with INT3) changes from "H" to "L" June 2003 Page 1 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 Figure 1 ADC Block Diagram 3.0 Repeat Sweep Mode 1 Description In repeat sweep mode 1, groups of pins of the ADC can be selected as input sources. Once triggered, a conversion takes place on the selected pins and the results are stored in the ADC result registers corresponding to the selected channels. This is repeated until the ADC conversion start flag is disabled. No interrupt is generated on the completed conversions, but rather the ADC output registers are read to determine the converted values. These registers are detailed in the included sample code. For specific details, refer to the M16C/26 M16C/26 datasheet. Figure 2 and Figure 3 show the control registers for the ADC in Repeat Sweep Mode 1. REU05B0031-0100Z REU05B0031-0100Z June 2003 Page 2 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 Figure 2 ADC Control Registers In Repeat Sweep Mode 1 REU05B0031-0100Z REU05B0031-0100Z June 2003 Page 3 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 Figure 3 ADC Control Registers 4.0 Example Program The following example program demonstrates how to perform a conversion using the ADC with the following configuration. · Repeat sweep mode 1 conversions · 10 bit mode · Analog inputs 0-3 used · Sample and hold enabled · Vref connected · Conversion clock used will be fAD /4 (When f(Xin) is greater than 10 MHz, fAD must be divided) · Software conversion start REU05B0031-0100Z REU05B0031-0100Z June 2003 Page 4 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 5.0 Reference Renesas Technology Corporation Semiconductor Home Page http://www.renesas.com E-mail Support support_apl@renesas.com Data Sheets · M16C/26 M16C/26 datasheets, M30262eds.pdf User's Manual · M16C/20/60 M16C/20/60 C Language Programming Manual, 6020c.pdf · M16C/20/60 M16C/20/60 Software Manual, 6020software.pdf · MSV30262-SKP MSV30262-SKP or MSV-Mini26-SKP Quick start guide · MSV30262-SKP MSV30262-SKP or MSV-Mini26-SKP Users Manual · MDECE30262 MDECE30262 or MSV-Mini26-SKP Schematic 6.0 Software Code The sample software provided was compiled using the KNC30 KNC30 compiler. The program sets up the ADC to continuously perform conversions on channels 0 to 3. The code then repeatedly reads the results of those conversions. This code was written to run on the MSV30262 MSV30262 Starter Kit but can be modified for a user application. /* * DESCRIPTION: single_sweep.c * * * * PURPOSE: Outlines how to use the M16C/26 M16C/26 ADC in repeat sweep * * mode 1. On reset, reset, program repeatedly stores * * the results of the conversions in variables that can * * be examined using KD30 along with the MSV30262-SKP MSV30262-SKP * * or similar tool. * * * */ #include "sfr26.h" int TempStore0 = 0x0000; int TempStore1 = 0x0000; REU05B0031-0100Z REU05B0031-0100Z // Location where ADC0 result is stored // Location where ADC1 result is stored June 2003 Page 5 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 /* * * * * * * * * */ main PARAMETERS: None DESCRIPTION: Main function. Where program execution starts. Sets up the ADC then waits for interrupt to occur. RETURNS: Nothing void main (void){ adcon0 = 0X18; /* 00011000; /* AN0, single sweep mode, software trigger, fAD/4 ||||||||_analog input select bit 0 |||||||_analog input select bit 1 ||||||_analog input select bit 2 |||||_A/D operation mode select bit 0 ||||_A/D operation mode select bit 0 |||_trigger select bit ||_A/D conversion start flag |_frequency select bit */ adcon1 = 0X3D; /* 00111101; /* 10 bit mode, fAD/4, Vref connected, AN0-3 ||||||||_A/D sweep pin select bit 0 |||||||_A/D sweep pin select bit 1 ||||||_A/D operation mode select bit 1 |||||_8/10 bit mode select bit ||||_Frequency select bit 1 |||_Vref connect bit ||_Reserved |_Reserved */ adcon2 = 0X01; /* 00000001; /* Sample and hold enabled, fAD/4 ||||||||_sample and hold select bit |||||||_reserved ||||||_reserved |||||_reserved ||||_Frequency select bit 2 |||_reserved ||_reserved |_reserved adst = 1; */ // Start a conversion here while (1){ REU05B0031-0100Z REU05B0031-0100Z June 2003 Page 6 of 7 M16C/26 M16C/26 Using the A-D Converter In Repeat Sweep Mode 1 TempStore0= ad0 & 0x03ff; // Mask off the upper 6 bits of the // Variable leaving only the result // in the variable itself TempStore1= ad1 & 0x03ff; // Mask off the upper 6 bits of the // Variable leaving only the result // in the variable itself } } REU05B0031-0100Z REU05B0031-0100Z June 2003 Page 7 of 7 Keep safety first in your circuit designs! · Renesas Technology Corporation puts the maximum effort into making semiconductor products better and more reliable, but there is always the possibility that trouble may occur with them. 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