1 /* bitbang_cbus.c
2
3 Example to use CBUS bitbang mode of newer chipsets.
4 You must enable CBUS bitbang mode in the EEPROM first.
5
6 Thanks to Steve Brown <sbrown@ewol.com> for the
7 the information how to do it.
8
9 The top nibble controls input/output and the bottom nibble
10 controls the state of the lines set to output. The datasheet isn't clear
11 what happens if you set a bit in the output register when that line is
12 conditioned for input. This is described in more detail
13 in the FT232R bitbang app note.
14
15 BITMASK
16 CBUS Bits
17 3210 3210
18 xxxx xxxx
19 | |------ Output Control 0->LO, 1->HI
20 |----------- Input/Output 0->Input, 1->Output
21
22 Example:
23 All pins to output with 0 bit high: 0xF1 (11110001)
24 Bits 0 and 1 to input, 2 and 3 to output and masked high: 0xCC (11001100)
25
26 The input is standard "0x" hex notation.
27 A carriage return terminates the program.
28
29 This program is distributed under the GPL, version 2
30 */
31
32 #include <stdio.h>
33 #include <unistd.h>
34 #include <stdlib.h>
35 #include <ftdi.h>
36
main(void)37 int main(void)
38 {
39 struct ftdi_context ftdic;
40 int f;
41 unsigned char buf[1];
42 unsigned char bitmask;
43 unsigned char input[10];
44
45 if (ftdi_init(&ftdic) < 0)
46 {
47 fprintf(stderr, "ftdi_init failed\n");
48 return EXIT_FAILURE;
49 }
50
51 f = ftdi_usb_open(&ftdic, 0x0403, 0x6001);
52 if (f < 0 && f != -5)
53 {
54 fprintf(stderr, "unable to open ftdi device: %d (%s)\n", f, ftdi_get_error_string(&ftdic));
55 exit(-1);
56 }
57 printf("ftdi open succeeded: %d\n",f);
58
59 while (1)
60 {
61 // Set bitmask from input
62 fgets(input, sizeof(input) - 1, stdin);
63 if (input[0] == '\n') break;
64 bitmask = strtol(input, NULL, 0);
65 printf("Using bitmask 0x%02x\n", bitmask);
66 f = ftdi_set_bitmode(&ftdic, bitmask, BITMODE_CBUS);
67 if (f < 0)
68 {
69 fprintf(stderr, "set_bitmode failed for 0x%x, error %d (%s)\n", bitmask, f, ftdi_get_error_string(&ftdic));
70 exit(-1);
71 }
72
73 // read CBUS
74 f = ftdi_read_pins(&ftdic, &buf[0]);
75 if (f < 0)
76 {
77 fprintf(stderr, "read_pins failed, error %d (%s)\n", f, ftdi_get_error_string(&ftdic));
78 exit(-1);
79 }
80 printf("Read returned 0x%01x\n", buf[0] & 0x0f);
81 }
82 printf("disabling bitbang mode\n");
83 ftdi_disable_bitbang(&ftdic);
84
85 ftdi_usb_close(&ftdic);
86 ftdi_deinit(&ftdic);
87 }
88