brymen-dmm: style nits, apply comm param defaults, low battery warning

[libsigrok.git] / src / hardware / brymen-dmm / api.c

diff --git a/src/hardware/brymen-dmm/api.c b/src/hardware/brymen-dmm/api.c
index 01e56112491832eb00f7e19924d4c1d165c4eb80..dacbee889267f7949e4e18ca08daa20ef31110b3 100644 (file)
--- a/src/hardware/brymen-dmm/api.c
+++ b/src/hardware/brymen-dmm/api.c
@@ -41,6 +41,7 @@ static GSList *brymen_scan(struct sr_dev_driver *di, const char *conn,
        struct sr_dev_inst *sdi;
        struct dev_context *devc;
        struct sr_serial_dev_inst *serial;
+       int rts_toggle_delay_us;
        GSList *devices;
        int ret;
        uint8_t buf[128];
@@ -50,6 +51,21 @@ static GSList *brymen_scan(struct sr_dev_driver *di, const char *conn,
 
        if (serial_open(serial, SERIAL_RDWR) != SR_OK)
                return NULL;
+       /*
+        * The device requires an RTS *pulse* before communication.
+        * The vendor's documentation recommends the following sequence:
+        * Open the COM port, wait for 100ms, set RTS=1, wait for 100ms,
+        * set RTS=0, wait for 100ms, set RTS=1, configure bitrate and
+        * frame format, transmit request data, receive response data.
+        */
+       rts_toggle_delay_us = 100 * 1000; /* 100ms */
+       g_usleep(rts_toggle_delay_us);
+       serial_set_handshake(serial, 1, -1);
+       g_usleep(rts_toggle_delay_us);
+       serial_set_handshake(serial, 0, -1);
+       g_usleep(rts_toggle_delay_us);
+       serial_set_handshake(serial, 1, -1);
+       g_usleep(rts_toggle_delay_us);
 
        sr_info("Probing port %s.", conn);
 
@@ -61,7 +77,7 @@ static GSList *brymen_scan(struct sr_dev_driver *di, const char *conn,
                goto scan_cleanup;
        }
 
-       len = 128;
+       len = sizeof(buf);
        ret = brymen_stream_detect(serial, buf, &len, brymen_packet_length,
                             brymen_packet_is_valid, 1000, 9600);
        if (ret != SR_OK)
@@ -95,7 +111,12 @@ static GSList *scan(struct sr_dev_driver *di, GSList *options)
 
        devices = NULL;
 
-       conn = serialcomm = NULL;
+       /*
+        * BEWARE! Default 'conn' is not desirable when the device cannot
+        * reliably get detected. Insist that users specify the port.
+        */
+       conn = NULL;
+       serialcomm = "9600/8n1/dtr=1/rts=1";
        for (l = options; l; l = l->next) {
                src = l->data;
                switch (src->key) {
@@ -110,10 +131,7 @@ static GSList *scan(struct sr_dev_driver *di, GSList *options)
        if (!conn)
                return NULL;
 
-       if (serialcomm)
-               devices = brymen_scan(di, conn, serialcomm);
-       else
-               devices = brymen_scan(di, conn, "9600/8n1/dtr=1/rts=1");
+       devices = brymen_scan(di, conn, serialcomm);
 
        return devices;
 }