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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 <config.h> | |
21 | #include "protocol.h" | |
22 | ||
23 | #define MAX_PACKET_LEN 22 | |
24 | ||
25 | /* Flags passed from the DMM. */ | |
26 | struct brymen_flags { | |
27 | gboolean is_low_batt, is_decibel, is_duty_cycle, is_hertz, is_amp; | |
28 | gboolean is_beep, is_ohm, is_fahrenheit, is_celsius, is_capacitance; | |
29 | gboolean is_diode, is_volt, is_dc, is_ac; | |
30 | }; | |
31 | ||
32 | struct bm850_command { | |
33 | uint8_t dle; | |
34 | uint8_t stx; | |
35 | uint8_t cmd; | |
36 | uint8_t arg[2]; | |
37 | uint8_t checksum; | |
38 | uint8_t dle2; | |
39 | uint8_t etx; | |
40 | }; | |
41 | ||
42 | struct brymen_header { | |
43 | uint8_t dle; | |
44 | uint8_t stx; | |
45 | uint8_t cmd; | |
46 | uint8_t len; | |
47 | }; | |
48 | ||
49 | struct brymen_tail { | |
50 | uint8_t checksum; | |
51 | uint8_t dle; | |
52 | uint8_t etx; | |
53 | }; | |
54 | ||
55 | /* | |
56 | * We only have one command because we only support the BM-857. However, the | |
57 | * driver is easily extensible to support more models, as the protocols are | |
58 | * very similar. | |
59 | */ | |
60 | enum { | |
61 | BM_CMD_REQUEST_READING = 0x00, | |
62 | }; | |
63 | ||
64 | static int bm_send_command(uint8_t command, uint8_t arg1, uint8_t arg2, | |
65 | struct sr_serial_dev_inst *serial) | |
66 | { | |
67 | struct bm850_command cmdout; | |
68 | int written; | |
69 | ||
70 | cmdout.dle = 0x10; | |
71 | cmdout.stx = 0x02; | |
72 | cmdout.cmd = command; | |
73 | cmdout.arg[0] = arg1; | |
74 | cmdout.arg[1] = arg2; | |
75 | cmdout.checksum = arg1 ^ arg2; | |
76 | cmdout.dle2 = 0x10; | |
77 | cmdout.etx = 0x03; | |
78 | ||
79 | /* TODO: How to compute the checksum? Hardware seems to ignore it. */ | |
80 | ||
81 | /* Request reading. */ | |
82 | written = serial_write_blocking(serial, &cmdout, sizeof(cmdout), | |
83 | serial_timeout(serial, sizeof(cmdout))); | |
84 | if (written != sizeof(cmdout)) | |
85 | return SR_ERR; | |
86 | ||
87 | return SR_OK; | |
88 | } | |
89 | ||
90 | SR_PRIV int brymen_packet_request(struct sr_serial_dev_inst *serial) | |
91 | { | |
92 | return bm_send_command(BM_CMD_REQUEST_READING, 0, 0, serial); | |
93 | } | |
94 | ||
95 | SR_PRIV int brymen_packet_length(const uint8_t *buf, int *len) | |
96 | { | |
97 | struct brymen_header *hdr; | |
98 | int packet_len; | |
99 | size_t buflen; | |
100 | ||
101 | buflen = *len; | |
102 | hdr = (void *)buf; | |
103 | ||
104 | /* Did we receive a complete header yet? */ | |
105 | if (buflen < sizeof(*hdr)) | |
106 | return PACKET_NEED_MORE_DATA; | |
107 | ||
108 | if (hdr->dle != 0x10 || hdr->stx != 0x02) | |
109 | return PACKET_INVALID_HEADER; | |
110 | ||
111 | /* Our packet includes the header, the payload, and the tail. */ | |
112 | packet_len = sizeof(*hdr) + hdr->len + sizeof(struct brymen_tail); | |
113 | ||
114 | /* In case we pick up an invalid header, limit our search. */ | |
115 | if (packet_len > MAX_PACKET_LEN) { | |
116 | sr_spew("Header specifies an invalid payload length: %i.", | |
117 | hdr->len); | |
118 | return PACKET_INVALID_HEADER; | |
119 | } | |
120 | ||
121 | *len = packet_len; | |
122 | sr_spew("Expecting a %d-byte packet.", *len); | |
123 | return PACKET_HEADER_OK; | |
124 | } | |
125 | ||
126 | SR_PRIV gboolean brymen_packet_is_valid(const uint8_t *buf) | |
127 | { | |
128 | struct brymen_header *hdr; | |
129 | struct brymen_tail *tail; | |
130 | int i; | |
131 | uint8_t chksum = 0; | |
132 | uint8_t *payload; | |
133 | ||
134 | payload = (uint8_t *)(buf + sizeof(struct brymen_header)); | |
135 | ||
136 | hdr = (void *)buf; | |
137 | tail = (void *)(payload + hdr->len); | |
138 | ||
139 | for (i = 0; i< hdr->len; i++) | |
140 | chksum ^= payload[i]; | |
141 | ||
142 | if (tail->checksum != chksum) { | |
143 | sr_dbg("Packet has invalid checksum 0x%.2x. Expected 0x%.2x.", | |
144 | chksum, tail->checksum); | |
145 | return FALSE; | |
146 | } | |
147 | ||
148 | return TRUE; | |
149 | } | |
150 | ||
151 | static int parse_value(const char *strbuf, int len, float *floatval) | |
152 | { | |
153 | int s, d; | |
154 | char str[32]; | |
155 | ||
156 | if (strstr(strbuf, "OL")) { | |
157 | sr_dbg("Overlimit."); | |
158 | *floatval = INFINITY; | |
159 | return SR_OK; | |
160 | } | |
161 | ||
162 | memset(str, 0, sizeof(str)); | |
163 | /* Spaces may interfere with parsing the exponent. Strip them. */ | |
164 | for (s = 0, d = 0; s < len; s++) { | |
165 | if (strbuf[s] != ' ') | |
166 | str[d++] = strbuf[s]; | |
167 | } | |
168 | if (sr_atof_ascii(str, floatval) != SR_OK) | |
169 | return SR_ERR; | |
170 | ||
171 | return SR_OK; | |
172 | } | |
173 | ||
174 | static void parse_flags(const uint8_t *buf, struct brymen_flags *info) | |
175 | { | |
176 | info->is_low_batt = (buf[4 + 3] & (1 << 7)) != 0; | |
177 | ||
178 | info->is_decibel = (buf[4 + 1] & (1 << 5)) != 0; | |
179 | info->is_duty_cycle = (buf[4 + 1] & (1 << 3)) != 0; | |
180 | info->is_hertz = (buf[4 + 1] & (1 << 2)) != 0; | |
181 | info->is_amp = (buf[4 + 1] & (1 << 1)) != 0; | |
182 | info->is_beep = (buf[4 + 1] & (1 << 0)) != 0; | |
183 | ||
184 | info->is_ohm = (buf[4 + 0] & (1 << 7)) != 0; | |
185 | info->is_fahrenheit = (buf[4 + 0] & (1 << 6)) != 0; | |
186 | info->is_celsius = (buf[4 + 0] & (1 << 5)) != 0; | |
187 | info->is_diode = (buf[4 + 0] & (1 << 4)) != 0; | |
188 | info->is_capacitance = (buf[4 + 0] & (1 << 3)) != 0; | |
189 | info->is_volt = (buf[4 + 0] & (1 << 2)) != 0; | |
190 | info->is_dc = (buf[4 + 0] & (1 << 1)) != 0; | |
191 | info->is_ac = (buf[4 + 0] & (1 << 0)) != 0; | |
192 | } | |
193 | ||
194 | SR_PRIV int brymen_parse(const uint8_t *buf, float *floatval, | |
195 | struct sr_datafeed_analog_old *analog, void *info) | |
196 | { | |
197 | struct brymen_flags flags; | |
198 | struct brymen_header *hdr; | |
199 | uint8_t *bfunc; | |
200 | int asciilen; | |
201 | ||
202 | (void)info; | |
203 | ||
204 | hdr = (void *)buf; | |
205 | bfunc = (uint8_t *)(buf + sizeof(struct brymen_header)); | |
206 | ||
207 | analog->mqflags = 0; | |
208 | ||
209 | /* Give some debug info about the package. */ | |
210 | asciilen = hdr->len - 4; | |
211 | sr_dbg("DMM flags: %.2x %.2x %.2x %.2x", | |
212 | bfunc[3], bfunc[2], bfunc[1], bfunc[0]); | |
213 | /* Value is an ASCII string. */ | |
214 | sr_dbg("DMM packet: \"%.*s\"", asciilen, bfunc + 4); | |
215 | ||
216 | parse_flags(buf, &flags); | |
217 | if (parse_value((const char *)(bfunc + 4), asciilen, floatval) != SR_OK) | |
218 | return SR_ERR; | |
219 | ||
220 | if (flags.is_volt) { | |
221 | analog->mq = SR_MQ_VOLTAGE; | |
222 | analog->unit = SR_UNIT_VOLT; | |
223 | } | |
224 | if (flags.is_amp) { | |
225 | analog->mq = SR_MQ_CURRENT; | |
226 | analog->unit = SR_UNIT_AMPERE; | |
227 | } | |
228 | if (flags.is_ohm) { | |
229 | if (flags.is_beep) | |
230 | analog->mq = SR_MQ_CONTINUITY; | |
231 | else | |
232 | analog->mq = SR_MQ_RESISTANCE; | |
233 | analog->unit = SR_UNIT_OHM; | |
234 | } | |
235 | if (flags.is_hertz) { | |
236 | analog->mq = SR_MQ_FREQUENCY; | |
237 | analog->unit = SR_UNIT_HERTZ; | |
238 | } | |
239 | if (flags.is_duty_cycle) { | |
240 | analog->mq = SR_MQ_DUTY_CYCLE; | |
241 | analog->unit = SR_UNIT_PERCENTAGE; | |
242 | } | |
243 | if (flags.is_capacitance) { | |
244 | analog->mq = SR_MQ_CAPACITANCE; | |
245 | analog->unit = SR_UNIT_FARAD; | |
246 | } | |
247 | if (flags.is_fahrenheit) { | |
248 | analog->mq = SR_MQ_TEMPERATURE; | |
249 | analog->unit = SR_UNIT_FAHRENHEIT; | |
250 | } | |
251 | if (flags.is_celsius) { | |
252 | analog->mq = SR_MQ_TEMPERATURE; | |
253 | analog->unit = SR_UNIT_CELSIUS; | |
254 | } | |
255 | if (flags.is_capacitance) { | |
256 | analog->mq = SR_MQ_CAPACITANCE; | |
257 | analog->unit = SR_UNIT_FARAD; | |
258 | } | |
259 | ||
260 | /* | |
261 | * The high-end Brymen models have a configurable reference impedance. | |
262 | * When the reference impedance is changed, the DMM sends one packet | |
263 | * with the value of the new reference impedance. Both decibel and ohm | |
264 | * flags are set in this case, so we must be careful to correctly | |
265 | * identify the value as ohm, not dBmW. | |
266 | */ | |
267 | if (flags.is_decibel && !flags.is_ohm) { | |
268 | analog->mq = SR_MQ_POWER; | |
269 | analog->unit = SR_UNIT_DECIBEL_MW; | |
270 | /* | |
271 | * For some reason, dBm measurements are sent by the multimeter | |
272 | * with a value three orders of magnitude smaller than the | |
273 | * displayed value. | |
274 | */ | |
275 | *floatval *= 1000; | |
276 | } | |
277 | ||
278 | if (flags.is_diode) | |
279 | analog->mqflags |= SR_MQFLAG_DIODE; | |
280 | /* We can have both AC+DC in a single measurement. */ | |
281 | if (flags.is_ac) | |
282 | analog->mqflags |= SR_MQFLAG_AC; | |
283 | if (flags.is_dc) | |
284 | analog->mqflags |= SR_MQFLAG_DC; | |
285 | ||
286 | if (flags.is_low_batt) | |
287 | sr_info("Low battery!"); | |
288 | ||
289 | return SR_OK; | |
290 | } |