SD_Card_Control

Page last updated 07 Apr 2018, by Kenji Arai. 0 replies

updated on April 7th, 2018

new updated information is below.

SD Card Control (New)

////////------------------- OLD INFORMATION ---------------------- ///////

Keywords: SD Card,  2GB,  Micro SD, LCD, Logger, File system, G sensor, RTC

Control Program

Reference

Function

Evey one second, five analog inputs are logged in SD-Card.
If you can use RTC function, you will get folliwng functions.
1. Time stamp in the file
2. One second period with high acuuracy
3. File name creates by time stamp then you can save several files with no overwrite condition

If you can connect TEXT LCD, you can see the data on the screen.
If you set up COM line via USB, you can also see DEBUG information from PC screen.

Hardware Configlation

Please refer following links
------- Sensors ---------

G-sensor  KX52-1050
Vref TL431
 Temperature sensor  LM60

------- Pin connection ------

Pin connection



Software

----- File name creation ------

 

    seconds = time(NULL);
    seconds %= 100000000;               // Adjust 8 charcters file name
    sprintf(buf,"/sd/%d.txt",seconds);  // File name is defined based on time from 1970/1/1   
    FILE *fp = fopen(buf, "w");         // Open "out.txt" on the local file system for writing

RTC has time infromation based on Jan. 1st, 1970. "seconds" is a second data since at the time.
This time infromation is always unique number then if it uses as  a file name, it doesn't need to consider conflicts.
The other hands, file name doesn't allow "Long File Name" on mbed current library.
So we need to keep 8 charcters for a file name then
seconds %= 100000000;
is very essential part to keep 8 characters.

 

Sample of logging data

This is a test program for logging /by JH1PJL
Time:07:19:35 PM, 2010/04/03
G-Sen, 0.813187, 0.282784, 0.262271  
VB, 0.310623, T, 0.350183  
G-Sen, 0.814164, 0.284005, 0.264713  
VB, 0.317216, T, 0.366789  
G-Sen, 0.814652, 0.284005, 0.263980  
VB, 0.317216, T, 0.367277  
G-Sen, 0.814896, 0.282784, 0.260806  
VB, 0.311844, T, 0.363126  
G-Sen, 0.813919, 0.284005, 0.264957  
VB, 0.317216, T, 0.367033  
G-Sen, 0.812698, 0.283028, 0.261783  
VB, 0.311600, T, 0.362393  
G-Sen, 0.814164, 0.283028, 0.262515  
VB, 0.311600, T, 0.361905  
G-Sen, 0.814164, 0.284249, 0.264225  
VB, 0.317460, T, 0.366545  
G-Sen, 0.814408, 0.283761, 0.264713  
VB, 0.313309, T, 0.364591  
G-Sen, 0.812454, 0.283761, 0.264469  
VB, 0.313309, T, 0.364103  
Time:07:19:45 PM, 2010/04/03
G-Sen, 0.813919, 0.283761, 0.264713  
VB, 0.313309, T, 0.364347  
G-Sen, 0.814408, 0.282540, 0.264469  
VB, 0.313553, T, 0.364835  

(delted contents)

G-Sen, 0.814408, 0.283028, 0.262515  
VB, 0.311600, T, 0.369963  
Time:07:21:05 PM, 2010/04/03
G-Sen, 0.812454, 0.283028, 0.262515  
VB, 0.311355, T, 0.370208  
G-Sen, 0.812698, 0.282784, 0.262515  
VB, 0.311600, T, 0.370696  
G-Sen, 0.812698, 0.283516, 0.264469  
VB, 0.317216, T, 0.374603  
G-Sen, 0.814164, 0.282784, 0.262271  
VB, 0.311600, T, 0.370696  
G-Sen, 0.814164, 0.284005, 0.264225  
VB, 0.313553, T, 0.372405  
G-Sen, 0.814164, 0.283761, 0.264469  
VB, 0.317216, T, 0.376068  
G-Sen, 0.814164, 0.284005, 0.264713  
VB, 0.313065, T, 0.373626  
G-Sen, 0.812698, 0.283761, 0.264469  
VB, 0.317460, T, 0.377045  
G-Sen, 0.814408, 0.283028, 0.262271  
VB, 0.311844, T, 0.373138  
G-Sen, 0.814164, 0.283028, 0.262271  
VB, 0.311844, T, 0.372894  
Time:07:21:15 PM, 2010/04/03
G-Sen, 0.814408, 0.284005, 0.263980  
VB, 0.317460, T, 0.376557  
Sampling numbers: 100


My Dirty Board

Picture1


Picture2

Debug screen on PC com

Micro-SD card which I'm using for this project

 

Another solution for File sytem

If you don't want to set up SD-Card interface hardware, you can use 2MB mbed data strage which you can see from PC as USB memory.
Follwing is a sample program for this.

Other related program

If you will make above mentioned several interfaces, you can use follwing programs to check each function.

------- Text LCD ---------

I used 40 charcters x 2 line type.
Following declaration is an essential.

TextLCD lcd(p22, p28, p27, p26, p25, p24, p23, 40, 2); // rs,rw,e,d0,d1,d2,d3,40char's x 2 lines

------  RTC Adjustment -------

Connect to 3V battery separate with 3.3V regulated voltage line. You set up this battery backup circuit then you can use RTC function.

 

Future improvement items

  1. Time stamp for File itself
  2. File acceess from Host (using USB Interface or LAN)

 

Revistion

April 3rd, 2010           Create this page
April 4th, 2010           Modify explanation

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