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 append_msg(char* newmsg, u8 wrap) {
27 char* dest = current_message[msg_length];
28 /* equivalent of a string copy */
38 void set_msg(char* newmsg, u8 wrap) {
40 append_msg(newmsg, wrap);
45 void display_shift() {
46 /* update the display for WRAP_SCROLL or WRAP_ALTERNATE modes */
51 if (scroll_point >= msg_length) scroll_point = 0;
57 void set_char(char c, u8 pos) {
58 /* sets a single character */
59 display_buffer[pos] = c;
63 void display_send_byte(char c) {
64 bset_misc_output(A3800_DISPLAY_WRITE); /* enable the display clock */
66 _io_ports[M6811_SPDR] = c; /* load SPI with byte */
67 while(!(_io_ports[M6811_SPDR]&M6811_SPIE)); /* wait for completion */
68 _io_ports[M6811_SPDR]; /* SPDR read to clear SPIE flag */
71 #define DISPLAY_DELAY 100 /* ms to delay between ops - could be tweaked */
72 void display_reset() {
73 /* lower the reset line for a while */
74 bclr((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
76 bset((void*)&_io_ports[M6811_PORTA], PORTA_DISP_RESET);
81 display_send_byte(0xC0 | 10); /* tell the controller there are 10 digits */
82 display_send_byte(0xE0); /* set duty cycle to 100% */
87 void display_update() {
90 for (i=0; i < 10; i++) {
91 display_buffer[i] = current_message[
92 (i+(wrap_mode==WRAP_ALTERNATE?scroll_point/10:scroll_point))
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() {