I am trying to transfer a bmp image from my sd card(from arduino) to my pc through serial.
I tried using the the sd card file dump(slightly modified to print out file stream in HEX) from the example, the output string i get seem to have some padding problems.
been trying to hours. dont know what is wrong. anyone know y?
/*
SD card file dump
This example shows how to read a file from the SD card using the
SD library and send it over the serial port.
The circuit:
* SD card attached to SPI bus as follows:
** MOSI - pin 11
** MISO - pin 12
** CLK - pin 13
** CS - pin 4 (for MKRZero SD: SDCARD_SS_PIN)
created 22 December 2010
by Limor Fried
modified 9 Apr 2012
by Tom Igoe
This example code is in the public domain.
*/
#include <SPI.h>
#include <SD.h>
const int chipSelect = 10;
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(115200);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.print("Initializing SD card...");
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
Serial.println("Card failed, or not present");
// don't do anything more:
return;
}
Serial.println("card initialized.\n\n");
// open the file. note that only one file can be open at a time,
// so you have to close this one before opening another.
File dataFile = SD.open("frame000.bmp");
// if the file is available, write to it:
if (dataFile) {
while (dataFile.available()) {
Serial.print(dataFile.read(), HEX);
}
dataFile.close();
Serial.println("\n\nEnd of file.");
}
// if the file isn't open, pop up an error:
else {
Serial.println("error opening datalog.txt");
}
}
void loop() {
}
i am trying to send and receive bmp files from the arduino to my android app on my phone.
planning to send a bmp file in the sd breakout of arduino to the phone by sending a string of hex through the serial(bluetooth) to my android app. and the android app will convert from hex to bmp.
when sending from arduino to android app, i keep getting the above error, where there arent sufficient number of 0s between.
I am trying to transfer a bmp image from my sd card(from arduino) to my pc through serial.
I tried using the the sd card file dump(slightly modified to Serial.print(dataFile.read(), HEX); to print it out in HEX).
the output string i get seem to have half the 0s
the output from arduino on serial monitor:
424D3A 0000000 360002800010001000101800000400011B0011B00000000006066F90
the actual correct output according to online file to hex converter:
424D3A 0000000 0000000 36000000280000000100000001000000010018000000000004000000110B0000110B000000000000000000006066F900
As coloured, the output from arduino on serial monitor seem to only half the number of 0s as the actual correct output.
the others are all correct
Serial.print has leading zero suppression.
Use Serial.write instead to transfer the exact byte.
i am trying to send a string of hex to my smartphone app through serial. i will need the byte to be converted to hex before sending.
is there any way of doing so?
sending binary data is a little too slow for large files, even at 115200 baud rate
So, you made sending data faster by sending two characters for every byte in the file.
I'm sure that that's much faster. You could speed that up even more by sending "eighty", instead of "80". Course, that will take a bit of fancy coding...
Grumpy_Mike:
The best way is not to send them as an ASCII string in the first place. But as my teacher used to say " it's your own time you are wasting".
byte convertFromHex(byte ascii){
if(ascii > 0x39) ascii -= 7; // adjust for hex letters upper or lower case
return(ascii & 0xf);
}
where s0 is the most significant ASCII byte and s1 is the least significant ASCII byte .
hi, thanks for your help grumpy_mike, i see that you helped someone asking similar question 3years back. but he does things a little differently than me so i cant rly use the solution in there.
just making sure, in the case of hex, for example, 0x4D.
s0 = 4,
s1 = D,
am i right to assume so? i am kinda confused what is going on haha
edit: oh i just saw your MSB and LSB line. cant seem to get the right conversion shall try again
Grumpy_Mike:
The best way is not to send them as an ASCII string in the first place. But as my teacher used to say " it's your own time you are wasting".
Grumpy_Mike:
No.
However what you are doing I haven't got a clue.
What is all this about?
if(s0 == '|' || s1 == '|')
The variables s0 and s1 are the two bytes you receive as ASCII characters. That code is seriously weird, can you explain what you think it is doing?
YES ITS WORKING. THANKS DUDE!!! :D:D:D:D:D
it appears its bad coding on my side. i did not take into account that the serial buffer could be empty after read() to s0, making s1 sometimes get unknown values(due to buffer empty).
my program works like this
enter a custom command, executes receiveHexDump() function
the receiveHexDump() function waits endlessly for the hex string, until the terminator '|' is received
the function reads the first 2bytes off the buffer, converts it to byte/bin, and writes to the .bmp image
when it reads '|' off the buffer, it means the bmp file write operation is complete. and it gets out of the receiveHexDump() function.
Heres how my code looks like after refining:
it now ensures there is something in the buffer before writing.
shall try again