2 * display.c - functions for controlling the display on the vending machine.
4 * Use set_msg(char*) to write a new message to the screen, replacing the
5 * previous one. The message can be at most 255 characters long. Use
6 * set_wrap_mode with one of the WRAP_* options in vend.h to set the scrolling
7 * behaviour. If the message is less than 10 characters, it is not scrolled.
8 * Otherwise, the message will scroll.
15 char display_buffer[10]; /* what each byte on the display reads */
16 char current_message[256]; /* message that is scrolled or switched between */
17 u8 msg_length; /* length of current_message */
18 u8 wrap_mode; /* whether to scroll or alternate between msgs */
19 u8 scroll_point; /* how far through the message we have scrolled */
21 /* private prototypes */
22 void display_send_byte(char c);
24 void display_update();
26 void set_msg(char* newmsg, u8 wrap) {
27 char* dest = current_message;
28 /* equivalent of a string copy */
29 /* while (dest++ = newmsg++); */
42 void display_shift() {
43 /* update the display for WRAP_SCROLL or WRAP_ALTERNATE modes */
47 if (scroll_point >= msg_length) scroll_point = 0;
52 if (scroll_point >= msg_length) scroll_point = 0;
53 /* the above means that only sets of multiples of 10 characters
54 * are shown (excess ones are not) */
59 void set_char(char c, u8 pos) {
60 /* sets a single character */
61 display_buffer[pos] = c;
65 void display_send_byte(char c) {
66 bset_misc_output(A3800_DISPLAY_WRITE); /* enable the display clock */
68 _io_ports[M6811_SPDR] = c; /* load SPI with byte */
69 while(!(_io_ports[M6811_SPDR]&M6811_SPIE)); /* wait for completion */
70 _io_ports[M6811_SPDR]; /* SPDR read to clear SPIE flag */
73 #define DISPLAY_DELAY 100 /* ms to delay between ops - could be tweaked */
74 void display_reset() {
75 /* lower the reset line for a while */
76 bclr((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
78 bset((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
83 display_send_byte(0xC0 | 10); /* tell the controller there are 10 digits */
84 display_send_byte(0xE0); /* set duty cycle to 100% */
89 void display_update() {
92 for (i=0; i < 10; i++) {
93 display_buffer[i] = current_message[(i+scroll_point)%msg_length];
96 /* hmmm, will this cause some flickering of the display? */
99 for (i=0; i < 10; i++) {
100 display_send_byte(display_buffer[i]&0x7f);
104 void display_init() {