Add LCD FPS testing utility

examples/board_hd44780/Makefile

@@ -33,9 +33,10 @@ LDFLAGS += -lpthread
 
 include ../Makefile.opengl
 
-all: obj atmega48_charlcd.axf ${target} 
+all: obj atmega48_charlcd.axf atmega48_fps_test.axf ${target} 
 
 atmega48_charlcd.axf: atmega48_charlcd.c
+atmega48_fps_test.axf: atmega48_fps_test.c
 
 include ${simavr}/Makefile.common
 

examples/board_hd44780/atmega48_fps_test.c

@@ -0,0 +1,47 @@
+#undef F_CPU
+#define F_CPU 16000000
+
+#include <avr/io.h>
+
+#include "avr_mcu_section.h"
+AVR_MCU(F_CPU, "atmega48");
+
+#include "avr_hd44780.c"
+
+int main()
+{
+	hd44780_init();
+	/*
+	 * Clear the display.
+	 */
+	hd44780_outcmd(HD44780_CLR);
+	hd44780_wait_ready(1); // long wait
+
+	/*
+	 * Entry mode: auto-increment address counter, no display shift in
+	 * effect.
+	 */
+	hd44780_outcmd(HD44780_ENTMODE(1, 0));
+	hd44780_wait_ready(0);
+
+	/*
+	 * Enable display, activate non-blinking cursor.
+	 */
+	hd44780_outcmd(HD44780_DISPCTL(1, 1, 0));
+	hd44780_wait_ready(0);
+
+	uint16_t count = 0;
+	while (1)
+	{
+		uint16_t temp = count;
+		for (uint8_t i = 5; i > 0; i--)
+		{
+			hd44780_outcmd(HD44780_DDADDR(i - 1));
+			hd44780_wait_ready(0);
+			hd44780_outdata(temp % 10 + 48);
+			temp /= 10;
+			hd44780_wait_ready(0);
+		}
+		count++;
+	}
+}

examples/board_hd44780/charlcd.c

@@ -146,11 +146,15 @@ main(
 		char *argv[])
 {
 	elf_firmware_t f = {{0}};
-	const char * fname = "atmega48_charlcd.axf";
+	const char *fname = argc > 1 ? argv[1] : "atmega48_charlcd.axf";
 //	char path[256];
 //	sprintf(path, "%s/%s", dirname(argv[0]), fname);
 //	printf("Firmware pathname is %s\n", path);
-	elf_read_firmware(fname, &f);
+	if (elf_read_firmware(fname, &f) == -1)
+	{
+		fprintf(stderr, "Unable to load firmware from file %s\n", fname);
+		exit(EXIT_FAILURE);
+	};
 
 	printf("firmware %s f=%d mmcu=%s\n", fname, (int) f.frequency, f.mmcu);