jsiConsolePrint(); usage example?

jsiConsolePrintf is like printf (I'd google it)... It needs a format string at the start which specifies what the next arguments actually are.

In Espruino I added some special format characters for JS variables, see this

So you want to do something like:

for(i = 0; i < 128; ++i)
    jsiConsolePrintf("%d, ", in[i]);
  jsiConsolePrintf("\n");

That'll output a comma-separated list of numbers. If you want to output just the actual character you can use %c - jsiConsolePrintf("%c", in[i]);.

jsiConsolePrint itself expects a C string - that's a pointer to a list of characters that is terminated with a 0 character, so you won't be able to just pass in the character itself.

If you did want to use it, you'd have to do:

char buf[2];
buf[0] = myCharacter;
buf[1] = 0;
jsiConsolePrint(buf);

(Of course you could also use jsiConsolePrintChar, which is probably what you want)

... anyway, it's just one of the many reasons that programming embedded devices in C is painful :)