Merge pull request #4 from labstreaminglayer/fix_unsigned_int

Fix unsigned int bug when pushing integers instead of floats

Author: cboulay

README.md

@@ -6,7 +6,7 @@ Streams analog input data from [Measurement Computing](https://www.mccdaq.com/)
 
 - Continuous hardware-paced acquisition via `ulAInScan` (no dropped samples)
 - **Scaled mode**: calibrated voltage output as `cf_float32`
-- **Raw mode**: integer ADC counts matching device resolution (`cf_int16` for 12/16-bit, `cf_int32` for 18/24-bit)
+- **Raw mode**: integer ADC counts matching device resolution (`cf_int16` for 12/16-bit, `cf_int32` for 18/24-bit), offset by the midpoint (0V = 0).
 - LSL stream metadata includes voltage range, resolution, and scaling coefficients for offline reconstruction
 - Automatic FIFO overrun recovery (restarts scan transparently on USB scheduling delays)
 - Per-device capability queries: supported voltage ranges, resolution, max scan rate
@@ -145,7 +145,7 @@ Options:
   --high-chan N            High channel (default: 5)
   -r, --rate RATE         Sample rate in Hz (default: 16384)
   --range VALUE           Voltage range (uldaq Range enum value, default: auto)
-  --raw                   Output raw integer ADC counts instead of scaled voltage
+  --raw                   Output raw integer ADC instead of scaled voltage
 ```
 
 Examples:
@@ -160,7 +160,7 @@ MCCOutletCLI --list-ranges -d 0
 # Stream 6 channels at 16384 Hz (scaled voltage)
 MCCOutletCLI -d 0 --low-chan 0 --high-chan 5 --rate 16384
 
-# Stream raw ADC counts
+# Stream raw ADC integers
 MCCOutletCLI --raw --device-name USB-1608FS
 
 # Use a config file
@@ -192,14 +192,14 @@ Outputs calibrated voltage as `cf_float32`. Channel units are volts (`V`).
 
 ### Raw Mode (`--raw`)
 
-Outputs uncalibrated ADC counts. The LSL channel format is selected based on the device's ADC resolution:
+Outputs uncalibrated ADC offset by midpoint (0=0). The LSL channel format is selected based on the device's ADC resolution:
 
-| ADC Resolution | LSL Format  | Value Range         |
-|----------------|-------------|---------------------|
-| 12-bit         | `cf_int16`  | 0 - 4095            |
-| 16-bit         | `cf_int16`  | 0 - 65535           |
-| 18-bit         | `cf_int32`  | 0 - 262143          |
-| 24-bit         | `cf_int32`  | 0 - 16777215        |
+| ADC Resolution | LSL Format  | Value Range           |
+|----------------|-------------|-----------------------|
+| 12-bit         | `cf_int16`  | -2048 - 2047          |
+| 16-bit         | `cf_int16`  | -32768 - 32767        |
+| 18-bit         | `cf_int32`  | -116072 - 116071      |
+| 24-bit         | `cf_int32`  | -83886078 - 83886077  |
 
 ### Stream Metadata
 

src/cli/main.cpp

@@ -39,7 +39,7 @@ void printUsage(const char* program_name) {
               << "  --high-chan N            High channel (default: 7)\n"
               << "  -r, --rate RATE         Sample rate in Hz (default: 44100)\n"
               << "  --range VALUE           Voltage range (uldaq Range enum value, default: auto)\n"
-              << "  --raw                   Output raw integer ADC counts instead of scaled voltage\n"
+              << "  --raw                   Output raw integer ADC integers instead of scaled voltage\n"
               << "\n"
               << "Examples:\n"
               << "  " << program_name << " --list-devices\n"

src/core/include/mccoutlet/Config.hpp

@@ -21,7 +21,7 @@ struct AppConfig {
     int high_channel = 5;
     double sample_rate = 16384.0;
     int range = -1;  ///< uldaq Range enum value, -1 = auto-select first
-    bool scaled = true;  ///< true = calibrated voltage, false = raw ADC counts
+    bool scaled = true;  ///< true = calibrated voltage, false = raw ADC integers
 };
 
 class ConfigManager {

src/core/include/mccoutlet/Device.hpp

@@ -112,7 +112,7 @@ class MCCDevice : public IDevice {
         int high_channel = 7;
         double sample_rate = 44100.0;
         int range = -1;             ///< uldaq Range enum value, -1 = auto-select first
-        bool scaled = true;         ///< true = calibrated voltage (float), false = raw ADC counts (int)
+        bool scaled = true;         ///< true = calibrated voltage (float), false = raw ADC (int)
     };
 
     using StatusCallback = std::function<void(const std::string& message, bool is_error)>;

src/core/src/Device.cpp

@@ -537,9 +537,11 @@ bool MCCDevice::getDataInt32(std::vector<int32_t>& buffer, double& timestamp) {
             size_t read_offset =
                 (static_cast<size_t>(scans_read_) * channelCount) % total_buffer_elements;
 
+            const int64_t mid = 1LL << (capabilities_.resolution_bits - 1);
             for (size_t i = 0; i < num_elements; ++i) {
-                buffer[i] = static_cast<int32_t>(
+                auto raw = static_cast<int64_t>(
                     scan_buffer_[(read_offset + i) % total_buffer_elements]);
+                buffer[i] = static_cast<int32_t>(raw - mid);
             }
 
             scans_read_ += available;
@@ -581,9 +583,11 @@ bool MCCDevice::getDataInt16(std::vector<int16_t>& buffer, double& timestamp) {
             size_t read_offset =
                 (static_cast<size_t>(scans_read_) * channelCount) % total_buffer_elements;
 
+            const int32_t mid = 1 << (capabilities_.resolution_bits - 1);
             for (size_t i = 0; i < num_elements; ++i) {
-                buffer[i] = static_cast<int16_t>(
+                auto raw = static_cast<int32_t>(
                     scan_buffer_[(read_offset + i) % total_buffer_elements]);
+                buffer[i] = static_cast<int16_t>(raw - mid);
             }
 
             scans_read_ += available;

src/core/src/LSLOutlet.cpp

@@ -40,7 +40,7 @@ LSLOutlet::LSLOutlet(const DeviceInfo& info)
         double full_scale = std::pow(2.0, info.resolution_bits);
         double span = info.range_max - info.range_min;
         double slope = span / full_scale;
-        double offset = info.range_min;
+        double offset = (info.range_min + info.range_max) / 2.0;
         acq.append_child_value("scaling_slope", std::to_string(slope));
         acq.append_child_value("scaling_offset", std::to_string(offset));
     }

src/gui/MainWindow.ui

@@ -180,7 +180,7 @@
         </item>
         <item>
          <property name="text">
-          <string>Raw (Integer Counts)</string>
+          <string>Raw (Integer)</string>
          </property>
         </item>
        </widget>