F²MC-8L/16LX FAMILY MB90340 SPI COMMUNICATION TO EXTERNAL ADC. (for MAX1286) 8/16-BIT MICROCONTROLLER APPLICATION NOTE

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1 Fujitsu Microelectronics Europe Application Note MCU-AN E-V10 F²MC-8L/16LX FAMILY 8/16-BIT MICROCONTROLLER MB90340 SPI COMMUNICATION TO EXTERNAL ADC (for MAX1286) APPLICATION NOTE

2 Revision History Revision History Date V1.0; MWi Issue This document contains 14 pages. MCU-AN E-V Fujitsu Microelectronics Europe GmbH

3 Warranty and Disclaimer Warranty and Disclaimer To the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH restricts its warranties and its liability for all products delivered free of charge (eg. software include or header files, application examples, target boards, evaluation boards, engineering samples of IC s etc.), its performance and any consequential damages, on the use of the Product in accordance with (i) the terms of the License Agreement and the Sale and Purchase Agreement under which agreements the Product has been delivered, (ii) the technical descriptions and (iii) all accompanying written materials. In addition, to the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH disclaims all warranties and liabilities for the performance of the Product and any consequential damages in cases of unauthorised decompiling and/or reverse engineering and/or disassembling. Note, all these products are intended and must only be used in an evaluation laboratory environment. 1. Fujitsu Microelectronics Europe GmbH warrants that the Product will perform substantially in accordance with the accompanying written materials for a period of 90 days form the date of receipt by the customer. Concerning the hardware components of the Product, Fujitsu Microelectronics Europe GmbH warrants that the Product will be free from defects in material and workmanship under use and service as specified in the accompanying written materials for a duration of 1 year from the date of receipt by the customer. 2. Should a Product turn out to be defect, Fujitsu Microelectronics Europe GmbH s entire liability and the customer s exclusive remedy shall be, at Fujitsu Microelectronics Europe GmbH s sole discretion, either return of the purchase price and the license fee, or replacement of the Product or parts thereof, if the Product is returned to Fujitsu Microelectronics Europe GmbH in original packing and without further defects resulting from the customer s use or the transport. However, this warranty is excluded if the defect has resulted from an accident not attributable to Fujitsu Microelectronics Europe GmbH, or abuse or misapplication attributable to the customer or any other third party not relating to Fujitsu Microelectronics Europe GmbH. 3. To the maximum extent permitted by applicable law Fujitsu Microelectronics Europe GmbH disclaims all other warranties, whether expressed or implied, in particular, but not limited to, warranties of merchantability and fitness for a particular purpose for which the Product is not designated. 4. To the maximum extent permitted by applicable law, Fujitsu Microelectronics Europe GmbH s and its suppliers liability is restricted to intention and gross negligence. NO LIABILITY FOR CONSEQUENTIAL DAMAGES To the maximum extent permitted by applicable law, in no event shall Fujitsu Microelectronics Europe GmbH and its suppliers be liable for any damages whatsoever (including but without limitation, consequential and/or indirect damages for personal injury, assets of substantial value, loss of profits, interruption of business operation, loss of information, or any other monetary or pecuniary loss) arising from the use of the Product. Should one of the above stipulations be or become invalid and/or unenforceable, the remaining stipulations shall stay in full effect Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

4 Contents Contents REVISION HISTORY... 2 WARRANTY AND DISCLAIMER... 3 CONTENTS INTRODUCTION MAX ADC Connection to MB Communication Timing Read Cycle Timing of MAX X-Bits at end of communication Example Code Initial Functions and Declarations Flowchart C Code Read Data from ADC Flowchart C Code Example of usage of Get_ADC function in Main Function Flowchart C Code BIBLIOGRAPHY Related Documents MCU-AN E-V Fujitsu Microelectronics Europe GmbH

5 Introduction 0 Introduction This application note describes how to communicate via SPI using the MB90340-UART with an external ADC. In this note a MAX1286 from Maxime is used. Please note, that this document only gives a rough overview about the communication. The described source codes were written for understanding not for code size or speed. Neither interrupts nor timer were used. Time critical program code is always performed by simple flag polling or wait loops. Please also refer to the Application Note AN SPI for further SPI specification and nomenclature. Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

6 1 MAX1286 THIS CHAPTER DESCRIBES HOW TO COMMUNICATE WITH THE MAX1286 ADC 1.1 ADC The MAX1286 is a 150ksps, 12-Bit, 2-Channel Single-ended ADC. The MAX1286 has the following pin-out: Vcc 1 8 SCLK AIN1 2 7 DOUT AIN2 3 6 CNVST GND 4 5 REF Pin names: Vcc Power Supply (+ 5 volts) AIN1 Analog Input Channel 1 AIN2 Analog Input Channel 2 GND Ground SCLK Serial Clock Input DOUT Serial Data Output CNVST Conversion Start Input REF External Reference Voltage Input 1.2 Connection to MB90340 The ADC can be connected as in the following schematic. Please note, that no power supply pins and other MCU-Pins are drawn than those for the connection to the ADC. MCU-AN E-V Fujitsu Microelectronics Europe GmbH

7 1.3 Communication Timing SPI COMMUNICATION TO ADC Detailed description of the timing and timing parameters can be found in the corresponding datasheet of the MAX1286 ADC Read Cycle Timing of MAX1286 A read cycle (read Channel 1 from ADC) has the following bit timing (SPI-CPOL = 1, SPI- CPHA = 1): ~3Ls CNVST SCK DOUT D7 D6 D5 D4 D3 D2 D1 D0 The CNVST signal is performed by Port-Pin. The ADC conversion time is about 3 Ls. After this time reading from the ADC is allowed. Data sampling of the UART is performed at the rising edge of the SCK signal X-Bits at end of communication Because the ADC has a resolution of 12 bits and the UART can only read 8 bit frames synchronously, the read-out frame is 16 bit. The ADC sets the MSB of the 12 bit conversion data to the first bit. Because of this the last read 4 bits are not valid. SCK from UART 1 st 8 Bits 2 nd 8 Bits DOUT (SIN0) D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X X X X Therefore the read-out data has to be shifted 4 times right. The upper 4 bits have to be filled with 0 then. Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

8 1.4 Example Code The following code shows how to establish a SPI communication to the ADC Initial Functions and Declarations Flowchart InitUART InitPorts wait Set Baud rate Set clock inversion (ESCR-SCES = 1) Set clock delay (ECCR-SCDE = 1) Reception and Transmission enable Set Port-Register 9 to 0x00 Set Port 90 to Output for CNVST-Pin Init Port 0 for LED bargraph Argument: j Do loop from 0 to j Set Mode 2, enable SCLK, enable SOT Set MSB first MCU-AN E-V Fujitsu Microelectronics Europe GmbH

9 C Code void InitUART(void) { BGR0 = 15; // 1M 16 MHz ESCR0 = 0x01; // SCES = 1 => CPOL = 1 ECCR0 = 0x10; // SCDE = 1 => CPHA = 1 SCR0 = 0x03; // reception and transmission enable SMR0 = 0x83; // Mode 2, SCLK enable, SOT enable SSR0 = 0x04; // MSB first, no interrupts } void InitPorts(void) { // Bit#0: CNVST PDR9 = 0x00; DDR9 = 0x01; // All Low // P90 = CNVST (Start convert) } PDR0 = 0x00; DDR0 = 0xFF; // LED-Port on Flash-CAN-100P-340 void wait(unsigned char a) { unsigned char i; } for(i = 0; i < a; i++); Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

10 1.4.2 Read Data from ADC Flowchart Get_ADC Set CNVST=1 (PDR90 =1) Wait for 4 NOPs Set CNVST=0 (PDR90 =0) Wait for 5 Ls Write dummy data to produce SCK RDRF == 0? Y N Read reception data and shift left 4 times Write dummy data to produce SCK RDRF == 0? Y N Read reception data and shift right 4 times and OR it to the last data Return data to caller MCU-AN E-V Fujitsu Microelectronics Europe GmbH

11 C Code unsigned int Get_ADC(void) { unsigned int data; PDR9 = 0x01; #pragma asm NOP NOP NOP NOP #pragma endasm // Start convert PDR9 = 0x00; wait(1); // Conversion Time (5 Fs approx.) TDR0 = 0x00; // Set dummy data to produce SCK while (SSR0_RDRF == 0); data = (RDR0 << 4); // Read bits 11-4 TDR0 = 0x00; // Set dummy data to produce SCK while (SSR0_RDRF == 0); data = (RDR0 >> 4); // Read bits 3-0 } return data; Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

12 1.4.3 Example of usage of Get_ADC function in Main Function Flowchart main Call InitPorts Call InitUART Call Get_ADC Use upper 8 bits of ADC data and put result to the LEDs of the Starterkit Board (as bar graph) MCU-AN E-V Fujitsu Microelectronics Europe GmbH

13 C Code void main(void) { unsigned int adc; unsigned char data; InitPorts(); InitUART(); // Initialize CNVST, LEDs // Init UART for SPI communication while(1) { adc = Get_ADC(); data = ((adc >> 4) & 0xFF); // bits 11-4 } } if (data > 227) PDR0 = 0xFF; else if (data > 198) PDR0 = 0x7F; else if (data > 170) PDR0 = 0x3F; else if (data > 142) PDR0 = 0x1F; else if (data > 113) PDR0 = 0x0F; else if (data > 85) PDR0 = 0x07; else if (data > 57) PDR0 = 0x03; else if (data > 28) PDR0 = 0x01; else PDR0 = 0x00; Fujitsu Microelectronics Europe GmbH MCU-AN E-V10

14 Chapter 2 Bibliography 2 Bibliography THIS CHAPTER NAMES THE RELATED DOCUMENTS 2.1 Related Documents AN SPI Fujitsu Application Note about SPI Modes DS MAX1286-MAX1289 Maxime data sheet of MAX1286 MCU-AN E-V Fujitsu Microelectronics Europe GmbH