Home A - Z Changelog
Menu
Page Index

Blame

ebe99f Bob Green 2026-03-19 08:31:29
1 
# Machine Library
2
3
I've created a library targeting the hardware specific aspects of programming the Sbc-3. I believe that it should work with the other boards from [Mega Micros](https://mega-micros.co.uk/index.htm), but since I don't have access to anything but the Sbc-3, can't confirm that.
4
dca070 Bob Green 2026-05-21 09:36:22
5
::: info
b51540 Bob Green 2026-05-21 09:35:14
6
Note. if compiling for the 68000, you'll need to change the target cpu in `src/stdenv.mk` and `src/lib/Makefile` by changing the **CPU** macro.
dca070 Bob Green 2026-05-21 09:36:22
7
:::
ebe99f Bob Green 2026-03-19 08:31:29
8
To use the library, just include the following in your C sourcecode:
9
```c
10
#include <machine.h>
11
```
2a20d4 Bob Green 2026-03-21 15:03:23
12
13
## Serial I/O
14
b26e81 Bob Green 2026-03-21 15:10:58
15
```C
16
int _char_available(void);
17
char _getchar(void);
18
void _putchar(char c);
19
```
20
2a20d4 Bob Green 2026-03-21 15:03:23
21
## LED Control
22
There's a block of 10 leds (LD7 on the SBC3-b3), and six of them can be used for anything you like. Led1 is furthest from the cpu:
d90362 Bob Green 2026-03-21 15:03:37
23
2a20d4 Bob Green 2026-03-21 15:03:23
24
| LED # | Used for |
25
|:------|:---------|
26
| 1 | Indicates that the board is being powered via an external 5v supply. |
27
| 2 | Indicated that the board is being powered via the ATX power connector. |
28
| 3 | Connected to the ~RTS pin on the duart channel B. |
29
| 4 | Connected to the ~RTS pin on the duart channel A. |
30
| 5 | Available to user. |
31
| 6 | Available to user. |
32
| 7 | Available to user. |
33
| 8 | Available to user. |
34
| 9 | Available to user. |
35
| 10 | Available to user. |
91e139 Bob Green 2026-03-21 15:06:40
36
37
Two functions are provided, one to turn on a led, and another to turn it off.
38
39
```C
40
void set_led(int lednum);
41
void clear_led(int lednum);
42
```
43
Where `lednum` is an integer in the range of 5 through to 10, as per the table above. Any other value will be silently ignored.
0c5486 Bob Green 2026-03-24 15:10:57
44
b69dc8 Bob Green 2026-03-24 15:11:57
45
## PI/T
46
47
```C
48
void _pit_reset(void);
49
unsigned int _pit_get_counter(void);
50
unsigned int _pit_set_counter(unsigned int);
51
```
52
0c5486 Bob Green 2026-03-24 15:10:57
53
## Compact Flash
54
55
```C
56
void _cf_wait_busy(void);
57
void _cf_wait_data(void);
58
void cf_init(void);
59
int cf_read(uint8_t drive_num, uint32_t sector, uint8_t *buffer);
60
61
```
d83b67 Bob Green 2026-03-24 15:21:18
62
63
## Vectors and Interrupts
64
65
```C
9463ec Bob Green 2026-03-24 15:22:39
66
unsigned int *_get_vectors_base(void);
fc90ec Bob Green 2026-03-29 13:27:43
67
unsigned int get_isr_handler(int vector_number);
68
unsigned int set_isr_handler(int vector_number, void isr(void));
d83b67 Bob Green 2026-03-24 15:21:18
69
```
1e0c28 Bob Green 2026-05-21 09:47:07
70
`_get_vectors_base()` return the contents of the `ivr` register on the 68030 or 0 on the 68000.
41d04d Bob Green 2026-05-21 09:47:20
71
1e0c28 Bob Green 2026-05-21 09:47:07
72
`get_isr_handler` returns the address of the handler currently configured to handle the exception specified by `vector_number`.
41d04d Bob Green 2026-05-21 09:47:20
73
f80b2d Bob Green 2026-05-21 09:49:31
74
`set_isr_handler()` sets a handler for the exception specified by `vector_number`. It returns the address of the handler that it replaced, or `0xffffffff` if the `vector_number` is out of range.
633040 Bob Green 2026-03-24 15:33:07
75
f01b84 Bob Green 2026-03-24 15:41:57
76
## `$I^2c$` Bus
633040 Bob Green 2026-03-24 15:33:07
77
78
```C
79
```
398ef5 Bob Green 2026-05-21 09:41:14
80
81
## Safe Memory Access
82
83
```C
84
int peek(uint8_t *addr);
85
int poke(uint8_t *addr, uint8_t val);
86
```
87
`peek()` attempts to read a byte from memory, returning the value read, or -1 if the read failed due to a Bus Error. Similarly, `poke()` attempts to write a byte to memory, returning -1 on a Bus Error.