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1 | /* | |
2 | * This file is part of the libsigrok project. | |
3 | * | |
4 | * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com> | |
5 | * | |
6 | * This program is free software: you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation, either version 3 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
18 | */ | |
19 | ||
20 | #include "protocol.h" | |
21 | ||
22 | #define MAX_PACKET_LEN 22 | |
23 | ||
24 | /* Flags passed from the DMM. */ | |
25 | struct brymen_flags { | |
26 | gboolean is_low_batt, is_decibel, is_duty_cycle, is_hertz, is_amp; | |
27 | gboolean is_beep, is_ohm, is_fahrenheit, is_celsius, is_capacitance; | |
28 | gboolean is_diode, is_volt, is_dc, is_ac; | |
29 | }; | |
30 | ||
31 | struct bm850_command { | |
32 | uint8_t dle; | |
33 | uint8_t stx; | |
34 | uint8_t cmd; | |
35 | uint8_t arg[2]; | |
36 | uint8_t checksum; | |
37 | uint8_t dle2; | |
38 | uint8_t etx; | |
39 | }; | |
40 | ||
41 | struct brymen_header { | |
42 | uint8_t dle; | |
43 | uint8_t stx; | |
44 | uint8_t cmd; | |
45 | uint8_t len; | |
46 | }; | |
47 | ||
48 | struct brymen_tail { | |
49 | uint8_t checksum; | |
50 | uint8_t dle; | |
51 | uint8_t etx; | |
52 | }; | |
53 | ||
54 | /* | |
55 | * We only have one command because we only support the BM-857. However, the | |
56 | * driver is easily extensible to support more models, as the protocols are | |
57 | * very similar. | |
58 | */ | |
59 | enum { | |
60 | BM_CMD_REQUEST_READING = 0x00, | |
61 | }; | |
62 | ||
63 | static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2, | |
64 | struct sr_serial_dev_inst *serial) | |
65 | { | |
66 | struct bm850_command cmdout; | |
67 | int written; | |
68 | ||
69 | cmdout.dle = 0x10; | |
70 | cmdout.stx = 0x02; | |
71 | cmdout.cmd = command; | |
72 | cmdout.arg[0] = arg1; | |
73 | cmdout.arg[1] = arg2; | |
74 | cmdout.checksum = arg1 ^ arg2; | |
75 | cmdout.dle2 = 0x10; | |
76 | cmdout.etx = 0x03; | |
77 | ||
78 | /* TODO: How to compute the checksum? Hardware seems to ignore it. */ | |
79 | ||
80 | /* Request reading. */ | |
81 | written = serial_write_blocking(serial, &cmdout, sizeof(cmdout), 0); | |
82 | if (written != sizeof(cmdout)) | |
83 | return SR_ERR; | |
84 | ||
85 | return SR_OK; | |
86 | } | |
87 | ||
88 | SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial) | |
89 | { | |
90 | return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial); | |
91 | } | |
92 | ||
93 | SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len) | |
94 | { | |
95 | struct brymen_header *hdr; | |
96 | int packet_len; | |
97 | size_t buflen; | |
98 | ||
99 | buflen = *len; | |
100 | hdr = (void *)buf; | |
101 | ||
102 | /* Did we receive a complete header yet? */ | |
103 | if (buflen < sizeof(*hdr)) | |
104 | return PACKET_NEED_MORE_DATA; | |
105 | ||
106 | if (hdr->dle != 0x10 || hdr->stx != 0x02) | |
107 | return PACKET_INVALID_HEADER; | |
108 | ||
109 | /* Our packet includes the header, the payload, and the tail. */ | |
110 | packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail); | |
111 | ||
112 | /* In case we pick up an invalid header, limit our search. */ | |
113 | if (packet_len > MAX_PACKET_LEN) { | |
114 | sr_spew("Header specifies an invalid payload length: %i.", | |
115 | hdr->len); | |
116 | return PACKET_INVALID_HEADER; | |
117 | } | |
118 | ||
119 | *len = packet_len; | |
120 | sr_spew("Expecting a %d-byte packet.", *len); | |
121 | return PACKET_HEADER_OK; | |
122 | } | |
123 | ||
124 | SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf) | |
125 | { | |
126 | struct brymen_header *hdr; | |
127 | struct brymen_tail *tail; | |
128 | int i; | |
129 | uint8_t chksum = 0; | |
130 | uint8_t *payload; | |
131 | ||
132 | payload = (uint8_t *)(buf + sizeof(struct brymen_header)); | |
133 | ||
134 | hdr = (void *)buf; | |
135 | tail = (void *)(payload + hdr->len); | |
136 | ||
137 | for (i = 0; i< hdr->len; i++) | |
138 | chksum ^= payload[i]; | |
139 | ||
140 | if (tail->checksum != chksum) { | |
141 | sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x.", | |
142 | chksum, tail->checksum); | |
143 | return FALSE; | |
144 | } | |
145 | ||
146 | return TRUE; | |
147 | } | |
148 | ||
149 | static int parse_value(const char *strbuf, int len, float *floatval) | |
150 | { | |
151 | int s, d; | |
152 | char str[32]; | |
153 | ||
154 | if (strstr(strbuf, "OL")) { | |
155 | sr_dbg("Overlimit."); | |
156 | *floatval = INFINITY; | |
157 | return SR_OK; | |
158 | } | |
159 | ||
160 | memset(str, 0, sizeof(str)); | |
161 | /* Spaces may interfere with parsing the exponent. Strip them. */ | |
162 | for (s = 0, d = 0; s < len; s++) { | |
163 | if (strbuf[s] != ' ') | |
164 | str[d++] = strbuf[s]; | |
165 | } | |
166 | if (sr_atof_ascii(str, floatval) != SR_OK) | |
167 | return SR_ERR; | |
168 | ||
169 | return SR_OK; | |
170 | } | |
171 | ||
172 | static void parse_flags(const uint8_t *buf, struct brymen_flags *info) | |
173 | { | |
174 | info->is_low_batt = (buf[4 + 3] & (1 << 7)) != 0; | |
175 | ||
176 | info->is_decibel = (buf[4 + 1] & (1 << 5)) != 0; | |
177 | info->is_duty_cycle = (buf[4 + 1] & (1 << 3)) != 0; | |
178 | info->is_hertz = (buf[4 + 1] & (1 << 2)) != 0; | |
179 | info->is_amp = (buf[4 + 1] & (1 << 1)) != 0; | |
180 | info->is_beep = (buf[4 + 1] & (1 << 0)) != 0; | |
181 | ||
182 | info->is_ohm = (buf[4 + 0] & (1 << 7)) != 0; | |
183 | info->is_fahrenheit = (buf[4 + 0] & (1 << 6)) != 0; | |
184 | info->is_celsius = (buf[4 + 0] & (1 << 5)) != 0; | |
185 | info->is_diode = (buf[4 + 0] & (1 << 4)) != 0; | |
186 | info->is_capacitance = (buf[4 + 0] & (1 << 3)) != 0; | |
187 | info->is_volt = (buf[4 + 0] & (1 << 2)) != 0; | |
188 | info->is_dc = (buf[4 + 0] & (1 << 1)) != 0; | |
189 | info->is_ac = (buf[4 + 0] & (1 << 0)) != 0; | |
190 | } | |
191 | ||
192 | SR_PRIV int brymen_parse(const uint8_t *buf, float *floatval, | |
193 | struct sr_datafeed_analog *analog, void *info) | |
194 | { | |
195 | struct brymen_flags flags; | |
196 | struct brymen_header *hdr; | |
197 | uint8_t *bfunc; | |
198 | int asciilen; | |
199 | ||
200 | (void)info; | |
201 | ||
202 | hdr = (void *)buf; | |
203 | bfunc = (uint8_t *)(buf + sizeof(struct brymen_header)); | |
204 | ||
205 | analog->mqflags = 0; | |
206 | ||
207 | /* Give some debug info about the package. */ | |
208 | asciilen = hdr->len - 4; | |
209 | sr_dbg("DMM flags: %.2x %.2x %.2x %.2x", | |
210 | bfunc[3], bfunc[2], bfunc[1], bfunc[0]); | |
211 | /* Value is an ASCII string. */ | |
212 | sr_dbg("DMM packet: \"%.*s\"", asciilen, bfunc + 4); | |
213 | ||
214 | parse_flags(buf, &flags); | |
215 | if (parse_value((const char *)(bfunc + 4), asciilen, floatval) != SR_OK) | |
216 | return SR_ERR; | |
217 | ||
218 | if (flags.is_volt) { | |
219 | analog->mq = SR_MQ_VOLTAGE; | |
220 | analog->unit = SR_UNIT_VOLT; | |
221 | } | |
222 | if (flags.is_amp) { | |
223 | analog->mq = SR_MQ_CURRENT; | |
224 | analog->unit = SR_UNIT_AMPERE; | |
225 | } | |
226 | if (flags.is_ohm) { | |
227 | if (flags.is_beep) | |
228 | analog->mq = SR_MQ_CONTINUITY; | |
229 | else | |
230 | analog->mq = SR_MQ_RESISTANCE; | |
231 | analog->unit = SR_UNIT_OHM; | |
232 | } | |
233 | if (flags.is_hertz) { | |
234 | analog->mq = SR_MQ_FREQUENCY; | |
235 | analog->unit = SR_UNIT_HERTZ; | |
236 | } | |
237 | if (flags.is_duty_cycle) { | |
238 | analog->mq = SR_MQ_DUTY_CYCLE; | |
239 | analog->unit = SR_UNIT_PERCENTAGE; | |
240 | } | |
241 | if (flags.is_capacitance) { | |
242 | analog->mq = SR_MQ_CAPACITANCE; | |
243 | analog->unit = SR_UNIT_FARAD; | |
244 | } | |
245 | if (flags.is_fahrenheit) { | |
246 | analog->mq = SR_MQ_TEMPERATURE; | |
247 | analog->unit = SR_UNIT_FAHRENHEIT; | |
248 | } | |
249 | if (flags.is_celsius) { | |
250 | analog->mq = SR_MQ_TEMPERATURE; | |
251 | analog->unit = SR_UNIT_CELSIUS; | |
252 | } | |
253 | if (flags.is_capacitance) { | |
254 | analog->mq = SR_MQ_CAPACITANCE; | |
255 | analog->unit = SR_UNIT_FARAD; | |
256 | } | |
257 | ||
258 | /* | |
259 | * The high-end Brymen models have a configurable reference impedance. | |
260 | * When the reference impedance is changed, the DMM sends one packet | |
261 | * with the value of the new reference impedance. Both decibel and ohm | |
262 | * flags are set in this case, so we must be careful to correctly | |
263 | * identify the value as ohm, not dBmW. | |
264 | */ | |
265 | if (flags.is_decibel && !flags.is_ohm) { | |
266 | analog->mq = SR_MQ_POWER; | |
267 | analog->unit = SR_UNIT_DECIBEL_MW; | |
268 | /* | |
269 | * For some reason, dBm measurements are sent by the multimeter | |
270 | * with a value three orders of magnitude smaller than the | |
271 | * displayed value. | |
272 | */ | |
273 | *floatval *= 1000; | |
274 | } | |
275 | ||
276 | if (flags.is_diode) | |
277 | analog->mqflags |= SR_MQFLAG_DIODE; | |
278 | /* We can have both AC+DC in a single measurement. */ | |
279 | if (flags.is_ac) | |
280 | analog->mqflags |= SR_MQFLAG_AC; | |
281 | if (flags.is_dc) | |
282 | analog->mqflags |= SR_MQFLAG_DC; | |
283 | ||
284 | if (flags.is_low_batt) | |
285 | sr_info("Low battery!"); | |
286 | ||
287 | return SR_OK; | |
288 | } |