I'm trying to add logging functionality to a sketch but I'm not able to find out how to make the code work. I'v googled it and tried different things but all I get is either a controller restart, a loooooong line with garbage or total freeze.
So how do I use sprintf_P to format a text string?
Some code:
const int formatBufferSize = 96;
const char logprefix01[] PROGMEM = "TMP";
const char logprefix02[] PROGMEM = "WPH";
const char logprefix03[] PROGMEM = "CFG";
const char logprefix04[] PROGMEM = "EEP";
const char logprefix05[] PROGMEM = "MAP";
const char logprefix06[] PROGMEM = "BAT";
const char logprefix07[] PROGMEM = "CHG";
const char logprefix08[] PROGMEM = "POW";
const char logprefix09[] PROGMEM = "ACT";
const char logprefix10[] PROGMEM = "LOG";
const char* const logPrefix[logtypeCount] = {
logprefix01,
logprefix02,
logprefix03,
logprefix04,
logprefix05,
logprefix06,
logprefix07,
logprefix08,
logprefix09,
logprefix10,
};
bool Logger::log(const int type, const char *msg)
{
char str[formatBufferSize];
// This lines casing the problem
sprintf_P(str, PSTR("%lu;%s;%ld;%s"), m_sequenceNumber, logPrefix[type], mega.getUnixtime(), msg);
return write(str);
}
bool Logger::write(const char *line)
{
// For debugging, just print the line.
Serial.print(F("LOGG:"));
Serial.println(line);
++m_sequenceNumber;
return true;
}
void setup()
{
// code...
logger.log(9, F("Startup"));
// more code...
}
Use %S instead of %s for strings in PROGMEM. Please see the documentation .
You probably shouldn't be using sprintf_P, it's a buffer overflow waiting to happen. Use snprintf_P and make sure the strings are always properly terminated.
Pieter
PieterP:%S instead of %s for strings in PROGMEM. Please see the documentation .
You probably shouldn't be using sprintf_P, it's a buffer overflow waiting to happen. Use snprintf_P and make sure the strings are always properly terminated.
Pieter
Thanks for the snprintf_P.
Tried this:
snprintf_P(str, formatBufferSize, PSTR("%lu;%S;%lu;%S"), m_sequenceNumber, logPrefix[type], mega.getUnixtime(), (__FlashStringHelper*)msg);
but still problems. This give me:
22:44:19.816 -> LOGG:37224448;]⸮@⸮⸮
22:44:19.816 -> ⸮ ⸮ ⸮⸮⸮q?⸮⸮
22:44:19.856 -> ⸮R⸮⸮⸮⸮⸮⸮⸮⸮⸮⸮ ⸮ ⸮oˁ⸮⸮q;121462809;b⸮⸮i⸮z⸮⸮/⸮⸮⸮⸮
PieterP
February 2, 2021, 10:25pm
4
The following code correctly prints 987654321;<STRING-1>;123456789;<STRING-2> when executed on an Arduino Leonardo:
void setup() {
Serial.begin(115200);
while(!Serial);
char buf[128]{};
static const char pstr1[] PROGMEM = "<STRING-1>";
static const char pstr2[] PROGMEM = "<STRING-2>";
unsigned long ul1 = 987654321;
unsigned long ul2 = 123456789;
snprintf_P(buf, sizeof(buf), PSTR("%lu;%S;%lu;%S"), ul1, pstr1, ul2, pstr2);
Serial.println(buf);
}
void loop() {}
Are your snprintf_P arguments the correct type? C-style variadic functions have no type checking whatsoever, so if you specify %lu and then pass an int instead of unsigned long, bad things happen ...
This version works. I had to add some to get it to compile.
const int formatBufferSize = 96;
const int logtypeCount = 10;
unsigned long m_sequenceNumber = 0;
const char logprefix01[] PROGMEM = "TMP";
const char logprefix02[] PROGMEM = "WPH";
const char logprefix03[] PROGMEM = "CFG";
const char logprefix04[] PROGMEM = "EEP";
const char logprefix05[] PROGMEM = "MAP";
const char logprefix06[] PROGMEM = "BAT";
const char logprefix07[] PROGMEM = "CHG";
const char logprefix08[] PROGMEM = "POW";
const char logprefix09[] PROGMEM = "ACT";
const char logprefix10[] PROGMEM = "LOG";
const char* const logPrefix[logtypeCount] =
{
logprefix01,
logprefix02,
logprefix03,
logprefix04,
logprefix05,
logprefix06,
logprefix07,
logprefix08,
logprefix09,
logprefix10,
};
class Logger
{
public:
Logger() {};
bool log(const int type, const char *msg);
bool write(const char *line);
};
bool Logger::log(const int type, const char *msg)
{
char str[formatBufferSize];
// This lines casing the problem
snprintf_P(str, formatBufferSize, PSTR("%lu;%S;%S"), m_sequenceNumber, logPrefix[type], msg);
return write(str);
}
bool Logger::write(const char *line)
{
// For debugging, just print the line.
Serial.print(F("LOGG:"));
Serial.println(line);
++m_sequenceNumber;
return true;
}
Logger logger;
void setup()
{
Serial.begin(115200);
// code...
logger.log(9, (const char *) F("Startup"));
// more code...
}
void loop() {}
Instead of casting to (const char *) in the function call, declare the argument as const __FlashStringHelper * in the function header, that way you can overload the function to also take a string in ram.
const int formatBufferSize = 96;
const int logtypeCount = 10;
unsigned long m_sequenceNumber = 0;
const char logprefix01[] PROGMEM = "TMP";
const char logprefix02[] PROGMEM = "WPH";
const char logprefix03[] PROGMEM = "CFG";
const char logprefix04[] PROGMEM = "EEP";
const char logprefix05[] PROGMEM = "MAP";
const char logprefix06[] PROGMEM = "BAT";
const char logprefix07[] PROGMEM = "CHG";
const char logprefix08[] PROGMEM = "POW";
const char logprefix09[] PROGMEM = "ACT";
const char logprefix10[] PROGMEM = "LOG";
const char* const logPrefix[logtypeCount] =
{
logprefix01,
logprefix02,
logprefix03,
logprefix04,
logprefix05,
logprefix06,
logprefix07,
logprefix08,
logprefix09,
logprefix10,
};
class Logger
{
public:
Logger() {};
bool log(const int type, const char *msg);
bool log(const int type, const __FlashStringHelper *msg);
bool write(const char *line);
};
bool Logger::log(const int type, const char *msg)
{
char str[formatBufferSize];
// This lines casing the problem
snprintf_P(str, formatBufferSize, PSTR("%lu;%S;%s"), m_sequenceNumber, logPrefix[type], msg);
return write(str);
}
bool Logger::log(const int type, const __FlashStringHelper *msg)
{
char str[formatBufferSize];
// This lines casing the problem
snprintf_P(str, formatBufferSize, PSTR("%lu;%S;%S"), m_sequenceNumber, logPrefix[type], msg);
return write(str);
}
bool Logger::write(const char *line)
{
// For debugging, just print the line.
Serial.print(F("LOGG:"));
Serial.println(line);
++m_sequenceNumber;
return true;
}
Logger logger;
void setup()
{
Serial.begin(115200);
// code...
logger.log(9, F("Startup"));
logger.log(5, "battery");
char charge[] = "charge";
logger.log(6, charge);
// more code...
}
void loop() {}
A lot of thanks to both johnwasser and david_2018.
It worked (after I removed another bug. Noticed that the m_sequenceNumber was incidentally declared as a uint16_t).
system
June 3, 2021, 2:58am
8
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