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TEC control loop

master
Sebastien Bourdeauducq 2023-09-11 20:00:48 +08:00
parent 1b363e7de9
commit dd370499f8
1 changed files with 34 additions and 8 deletions
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42
main.cpp
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@ -33,6 +33,11 @@ static int waterfall_width = 1000;
static int waterfall_height = 2000;
static unsigned int waterfall_data[1000*2000];
static std::atomic<float> freq_setpoint;
static std::atomic<float> freq_peak;
static std::atomic<float> tec_bias;
static std::atomic<float> tec_p;
static std::atomic<int> fps;
static void dsp_thread() {
@ -47,10 +52,11 @@ static void dsp_thread() {
std::vector<std::complex<float>> frames_f(len);
pocketfft::shape_t shape{len};
pocketfft::stride_t stride(1);
stride[0] = 2*sizeof(float);
stride[0] = sizeof(std::complex<float>);
pocketfft::shape_t axes;
axes.push_back(0);
std::vector<std::complex<float>> frames_ft(len);
std::vector<std::complex<float>> frames_ft_rev(len);
std::vector<float> frames_mag(len);
int iterations = 0;
auto last_second = std::chrono::steady_clock::now();
@ -65,12 +71,22 @@ static void dsp_thread() {
// FFT
for(size_t i=0;i<len;i++)
frames_f[i] = frames[i];
pocketfft::c2c(shape, stride, stride, axes, pocketfft::FORWARD, frames_f.data(), frames_ft.data(), 1.0f);
pocketfft::c2c(shape, stride, stride, axes, pocketfft::FORWARD, frames_f.data(), frames_ft_rev.data(), 1.0f);
// negative frequencies first
for(size_t i=0;i<len/2;i++)
frames_mag[i] = abs(frames_ft_rev[i + len/2]);
for(size_t i=0;i<len/2;i++)
frames_mag[i + len/2] = abs(frames_ft_rev[i]);
// stabilize laser
if((std::chrono::steady_clock::now() - last_tec) >= 100ms) {
float freq_peak_local;
freq_peak_local = 40.0f*float(distance(frames_mag.begin(), max_element(frames_mag.begin(), frames_mag.end())))/float(len);
freq_peak = freq_peak_local;
// FIXME: net::write seems unimplemented as of libstdc++ 13
tec_socket.write_some(net::buffer(std::format(":SOUR2:VOLT {:.3f}\n", 0.1)));
float freq_error = freq_peak_local - freq_setpoint;
tec_socket.write_some(net::buffer(std::format(":SOUR2:VOLT {:.3f}\n",
std::min(tec_bias+tec_p*freq_error, 0.0f))));
last_tec += 100ms;
}
@ -80,9 +96,9 @@ static void dsp_thread() {
std::memmove(&waterfall_data[waterfall_width], &waterfall_data[0], sizeof(int)*waterfall_width*(waterfall_height - 1));
for(int i=0;i<waterfall_width;i++) {
int j = i*len/waterfall_width;
j = (j + len/2) % len; // display negative frequencies first
waterfall_data[i] = 0xff000000 | 0x010101*std::min(int(abs(frames_ft[j])/900.), 255);
waterfall_data[i] = 0xff000000 | 0x010101*std::min(int(frames_mag[j]/900.0f), 255);
}
waterfall_data[int(freq_setpoint*waterfall_width)/40] = 0xff0000ff;
}
// FPS counter
@ -192,6 +208,9 @@ int main(int argc, char* argv[])
bool exit = false;
bool update = true;
float freq_setpoint_local = 0.0f;
float tec_bias_local = 0.02f;
float tec_p_local = 0.001f;
while(!exit && !glfwWindowShouldClose(window)) {
glfwPollEvents();
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
@ -216,10 +235,17 @@ int main(int argc, char* argv[])
ImGui::Begin("fastsa", nullptr, ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoResize);
ImGui::BeginTable("fastsa", 2, ImGuiTableFlags_SizingStretchSame | ImGuiTableFlags_Resizable);
ImGui::TableSetupColumn("", 0, 280.0);
ImGui::TableSetupColumn("", 0, 1000.0);
ImGui::TableSetupColumn("", 0, 280.0f);
ImGui::TableSetupColumn("", 0, 1000.0f);
ImGui::TableNextColumn();
ImGui::Checkbox("Update", &update);
ImGui::Text("Peak: %.3f", (float)freq_peak);
ImGui::SliderFloat("Setpoint", &freq_setpoint_local, 0.0f, 40.0f);
ImGui::SliderFloat("TEC bias", &tec_bias_local, 0.0f, 0.5f);
ImGui::SliderFloat("TEC P", &tec_p_local, -0.05f, 0.05f);
freq_setpoint = freq_setpoint_local;
tec_bias = tec_bias_local;
tec_p = tec_p_local;
if(ImGui::Button("Exit"))
exit = true;
ImGui::Text("FPS: %d", (int)fps);