1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
;;
;; spreadspace pic utils
;;
;;
;; Copyright (C) 2011-2013 Christian Pointner <equinox@spreadspace.org>
;;
;; This file is part of spreadspace pic utils.
;;
;; spreadspace pic utils is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; any later version.
;;
;; spreadspace pic utils is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with spreadspace pic utils. If not, see <http://www.gnu.org/licenses/>.
;;
;; --- transmit byte and add it to csum
com_tx_byte
movwf SSPBUF
bcf INTPIN
xorwf csum,f
bsf STATUS,RP0
com_tx_byte_wait1
btfss SSPSTAT,BF
goto com_tx_byte_wait1
bcf STATUS,RP0
com_tx_byte_wait2 ; also wait for SS to go up again
btfss PORTA,5 ; this lowers the risk for raise conditions
goto com_tx_byte_wait2 ; with next byte (INT pin)
movf SSPBUF,w
bsf INTPIN
return
;; ---- wait for byte to be received
com_rx_byte
bsf STATUS,RP0
btfsc SSPSTAT,BF
goto com_rx_got_byte
bcf STATUS,RP0
btfss SSPCON,SSPOV
goto com_rx_byte
movf SSPBUF,w
bcf SSPCON,SSPOV
goto com_rx_byte
com_rx_got_byte
bcf STATUS,RP0
movf SSPBUF,w
return
;; ----- initialize com (this is called by bootmacro, it's not a subroutine - no return at the end)
com_init
;; bank 3 - we are already there, see bootmacro
;; bank 1
bcf STATUS,RP1
movlw b'01110000' ; set internal OSC to 8MHz
movwf OSCCON
movlw b'01000000' ; SMP=0,CKE=1
movwf SSPSTAT
bcf TRISC,5 ; RC5(SDO) = out
bcf INTPIN ; interrupt line to master
;; bank 0
bcf STATUS,RP0
btfsc BOOTPIN
goto USERVECT
movlw b'00100100' ; SSPEN=1,CKP=0,SSPM=0100(SPI Slave with SS)
movwf SSPCON
bsf INTPIN
|
