C / C++ / MFC

Jochen Arndt wrote:

That makes parsing much simpler (e.g. using scanf()) and you can wait for the known number of characters (11 + line feed):

const int CMD_LENGTH = 12; // Or whatever applies
while(n < CMD_LENGTH && i < 1000000);

By the way: what is the purpose of the undefined variable i here?

do{
            n = RS232_PollComport(cport_nr, (unsigned char *) str_recv, (int)BUF_SIZE);
            i++;
          }while(n <= 0 && i < 1000000);

            if(n > 0){
              str_recv[n] = 0;
              printf("Received %i bytes: '%s'\n", n, str_recv);

Jochen Arndt wrote:

But when doing so you will run more into the already existing performance problem of using a polling loop. Waiting for the data wastes a lot of time (10 ms) that is not available for other tasks.

The solution is to put the receiving into an own thread and use the fine Qt signaling features. Because there are only two event data values, there is even no need to use shared variables.

const int packetLength = 12;
int packetRead = 0;
while (packetRead < packetLength)
{
    // Append data to buffer
    int read = RS232_PollComport(cport_nr, (unsigned char *)str_recv + packetRead, (int)BUF_SIZE - packetRead);
    // Check for error
    if (read < 0)
    {
        return;
    }
    packetRead += read;
}
// Null terminate the buffer so that it can be used with string functions
// This will replace the trailing LF
str_recv[packetRead - 1] = 0;
// Get data from the received string
char cmd1, cmd2;
int val1, val2
sscanf(str_recv, "%c%03dE %c%03dE", &cmd1, &val1, &cmd2, &val2);
// Handle data here
if ('R' == cmd1)
    position = val1;
else
    position = -1;

Serial.println(dataToSend);

Quote:

The real question - how does "dev" framebuffer gets to output to "dev" SPI?

Quote:

Use the speed= argument to make it a SPI device, or else it becomes a platform_device

sudo modprobe fbtft_device name=rpi-display speed=32000000

struct fbcon_font_desc {
    int index ; // idx;
    char *name;
    int width, height;
    unsigned char *data;   // font data
    int pref;
} font_vga_8x8 = // this is the name of the actual structure variable
{
    VGA8x8_IDX,
    "VGA8x8",
    8,
    8,
    fontdata_8x8,
    0
};

struct fbcon_font_desc {
    int index ; // idx;
    char *name;
    int width, height;
    unsigned char *data;   // font data
    int pref;
};
// Type is struct fbcon_font_desc
struct fbcon_font_desc font_vga_8x8 = { /* init members here */ };

typedef struct {
    int index ; // idx;
    char *name;
    int width, height;
    unsigned char *data;   // font data
    int pref;
} fbcon_font_desc;
// Type is fbcon_font_desc
fbcon_font_desc font_vga_8x8 = { /* init members here */ };