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hantek-dso: calculate voltage based on vdiv setting

This commit is contained in:
Bert Vermeulen 2012-06-05 18:17:01 +02:00
parent a10c805636
commit c5841b2809
1 changed files with 13 additions and 3 deletions
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16
hardware/hantek-dso/api.c
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@ -555,7 +555,7 @@ static void receive_transfer(struct libusb_transfer *transfer)
struct sr_datafeed_packet packet;
struct sr_datafeed_analog analog;
struct context *ctx;
float ch1, ch2;
float ch1, ch2, range;
int num_probes, data_offset, i;
ctx = transfer->user_data;
@ -581,14 +581,24 @@ static void receive_transfer(struct libusb_transfer *transfer)
/* The device always sends data for both channels. If a channel
* is disabled, it contains a copy of the enabled channel's
* data. However, we only send the requested channels to the bus.
*
* Voltage values are encoded as a value 0-255 (0-512 on the 5200*),
* where the value is a point in the range represented by the vdiv
* setting. There are 8 vertical divs, so e.g. 500mV/div represents
* 4V peak-to-peak where 0 = -2V and 255 = +2V.
*/
/* TODO: support for 5xxx series 9-bit samples */
if (ctx->ch1_enabled) {
ch1 = (*(transfer->buffer + i * 2 + 1) / 255.0);
range = ((float)vdivs[ctx->voltage_ch1].p / vdivs[ctx->voltage_ch1].q) * 8;
ch1 = range / 255 * *(transfer->buffer + i * 2 + 1);
/* Value is centered around 0V. */
ch1 -= range / 2;
analog.data[data_offset++] = ch1;
}
if (ctx->ch2_enabled) {
ch2 = (*(transfer->buffer + i * 2) / 255.0);
range = ((float)vdivs[ctx->voltage_ch2].p / vdivs[ctx->voltage_ch2].q) * 8;
ch2 = range / 255 * *(transfer->buffer + i * 2);
ch2 -= range / 2;
analog.data[data_offset++] = ch2;
}
}