Nuts and Volts - October 2015

 //send new file command
 sprintf(cmdBuf,”new
 microsd%1d.csv\r”,filenum);
 sendStrUart2(cmdBuf);
 //wait for command mode prompt
 do{
 if(CharInQueue2())
 {
 bitein recvchar2();
 }
 }while(bitein ‘>’);
}
 //***********************************************
 //* LIST File
 //***********************************************
 void listFile(void)
 {
 char cmdBuf[32];
 WORD timeoutms;
 WORD i;
 BYTE bitein;
 U2TXREG (*buffer++);
 }
}
//***********************************************
//* CREATE NEW FILE
//***********************************************
void newFile(BYTE filenum)
{
 BYTE bitein;
 char cmdBuf[32];

The maximum length of our filenames is eight characters plus three characters behind the dot delineator (12345678.123). So, we can create up to 10 files with our filename of microsdX.csv, where X represents the filenum argument that can range from 0 through 9. The .csv extension allows us to read the file in a formatted manner using Microsoft Excel. The new command is issued from our PIC32MX575F512H firmware just as it would be manually (reference Screenshot 1).

 //send list file command
 sprintf(cmdBuf,”ls\r”);
 sendStrUart2(cmdBuf);
 //wait for card to respond to ls
 i 0;
 timeoutms 5000;
 do{
 if(CharInQueue2())
 {
 do{
 bitein recvchar2();
 sendBiteUart1(bitein);
 }while(CharInQueue2());
 }
 tdelayms(1);
 }while(timeoutms— && (bitein ‘>’));
}

The sprintf function writes the new command string into the cmdBuf array and appends a null character (0x00) to the command string. The null character is important as our sendStrUart2 function is looking for a null character to indicate the end of the string. Once the new command is transmitted to the OpenLog firmware, we wait for a > prompt following the completion of the command.

Again, we use the sprintf function to load and format our command string. And again, we send the ls command string using the sendStrUart2 function. If the OpenLog firmware doesn’t return a result in five seconds, we’ve got big problems to solve and probably would not have even gotten this far in our coding. So, we’ll wait for the file listing to flow to the PIC32MX575F512H’s UART2. Every character that is received by UART2 is forwarded to the transmit pin of UART1 (the FTDI USB portal). As you can see in Screenshot 3, everything is okay. There are currently two files on the microSD card we can list and both of them show up in our Screenshot 3 listing.

We can instantly verify that the file was created by utilizing the onboard FTDI USB portal. All we need is a simple piece of code targeting the ls command:

Write to Our New File

We have successfully created a file called

Original OpenLog Module SparkFun www.sparkfun.com PIC32MX575F512H XC32 C Compiler Microchip www.microchip.com Serial Input/Output Monitor CCS www.ccsinfo.com ATmega328P Atmel www.atmel.com PICBASIC Pro

■ Screenshot 3. This is exactly what we should have expected. The CONFIG. TXT file — which was created by the OpenLog firmware — and a newly created and empty MICROSD1.CSV file.