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 */
20 bool have_scrolled; /* true after one scroll (used for scroll_msg())*/
22 /* private prototypes */
23 void display_send_byte(char c);
25 void display_update();
27 void append_msg(char* newmsg, u8 wrap) {
28 char* dest = current_message+msg_length;
29 /* equivalent of a string copy */
39 void set_msg(char* newmsg, u8 wrap) {
41 append_msg(newmsg, wrap);
46 void scroll_msg(char* newmsg) {
47 /* puts a message on display and does not return until the message has
48 * scrolled across once.
50 set_msg(newmsg, WRAP_SCROLL);
52 while (!have_scrolled);
55 void display_shift() {
56 /* update the display for WRAP_SCROLL or WRAP_ALTERNATE modes */
61 if (scroll_point >= msg_length) {
70 void set_char(char c, u8 pos) {
71 /* sets a single character */
72 display_buffer[pos] = c;
76 void display_send_byte(char c) {
77 bset_misc_output(A3800_DISPLAY_WRITE); /* enable the display clock */
79 _io_ports[M6811_SPDR] = c; /* load SPI with byte */
80 while(!(_io_ports[M6811_SPDR]&M6811_SPIE)); /* wait for completion */
81 _io_ports[M6811_SPDR]; /* SPDR read to clear SPIE flag */
84 #define DISPLAY_DELAY 100 /* ms to delay between ops - could be tweaked */
85 void display_reset() {
86 /* lower the reset line for a while */
87 bclr((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
89 bset((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
94 display_send_byte(0xC0 | 10); /* tell the controller there are 10 digits */
95 display_send_byte(0xE0); /* set duty cycle to 100% */
100 void display_update() {
103 for (i=0; i < 10; i++) {
104 display_buffer[i] = current_message[
105 (i+(wrap_mode==WRAP_ALTERNATE?scroll_point/10:scroll_point))
109 /* hmmm, will this cause some flickering of the display? */
112 for (i=0; i < 10; i++) {
113 display_send_byte(display_buffer[i]&0x7f);
117 void display_init() {