// license:GPL-2.0+ // copyright-holders:Couriersud /* * nld_SN74LS629.c * */ /* * The 74LS624 series are constant current based VCOs. The Freq Control voltage * modulates the current source. The current is created from Rext, which is * internally fixed at 600 ohms for all devices except the 74LS628 which has * external connections. The current source linearly discharges the cap voltage. * The cap starts with 0V charge across it. One side is connected to a fixed voltage * bias circuit. The other side is charged negatively from the current source until * a certain low threshold is reached. Once this threshold is reached, the output * toggles state and the pins on the cap reverse in respect to the charge/bias hookup. * This starts the one side of the cap to be at bias, and the other side of the cap is * now at bias + the charge on the cap which is bias - threshold. * Y = 0; CX1 = bias; CX2 = charge * Y = 1; CX1 = charge; CX2 = bias * The Range voltage adjusts the threshold voltage. The higher the Range voltage, * the lower the threshold voltage, the longer the cap can charge, the lower the frequency. * * In a perfect world it would work like this: * The current is based on the mysterious Rext mentioned in the data sheet. * I = (VfreqControl * 20k/90k) / Rext * where Rext = 600 ohms or external Rext on a 74LS628 * The Freq Control has an input impedance of approximately 90k, so any input resistance * connected to the Freq Control pin works as a voltage divider. * I = (VfreqControl * 20k/(90k + RfreqControlIn)) / Rext * That gives us a change in voltage on the cap of * dV = I / sampleRate / C_inFarads * * Unfortunately the chip does not behave linearly do to internal interactions, * so I have just worked out the formula (using zunzun.com) of FreqControl and * range to frequency out for a fixed cap value of 0.1uf. Other cap values can just * scale from that. From the freq, we calculate the time of 1/2 cycle using 1/Freq/2. * Then just use that to toggle a waveform. */ #include "nld_74ls629.h" #include "nl_setup.h" NETLIB_NAMESPACE_DEVICES_START() NETLIB_START(SN74LS629clk) { register_input("FB", m_FB); register_output("Y", m_Y); connect_late(m_FB, m_Y); reset(); save(NLNAME(m_enableq)); save(NLNAME(m_inc)); save(NLNAME(m_out)); } NETLIB_RESET(SN74LS629clk) { m_enableq = 1; m_out = 0; m_inc = netlist_time::zero; } NETLIB_UPDATE(SN74LS629clk) { if (!m_enableq) { m_out = m_out ^ 1; OUTLOGIC(m_Y, m_out, m_inc); } else { OUTLOGIC(m_Y, 1, m_inc); } } NETLIB_START(SN74LS629) { register_sub("OSC", m_clock); register_sub("R_FC", m_R_FC); register_sub("R_RNG", m_R_RNG); register_input("ENQ", m_ENQ); register_input("RNG", m_RNG); register_input("FC", m_FC); register_subalias("GND", m_R_FC.m_N); connect_late(m_FC, m_R_FC.m_P); connect_late(m_RNG, m_R_RNG.m_P); connect_late(m_R_FC.m_N, m_R_RNG.m_N); register_subalias("Y", m_clock.m_Y); register_param("CAP", m_CAP, 1e-6); } NETLIB_RESET(SN74LS629) { m_R_FC.set_R(90000.0); m_R_RNG.set_R(90000.0); m_clock.reset(); } NETLIB_UPDATE(SN74LS629) { { // recompute nl_double freq; nl_double v_freq_2, v_freq_3, v_freq_4; nl_double v_freq = INPANALOG(m_FC); nl_double v_rng = INPANALOG(m_RNG); /* coefficients */ const nl_double k1 = 1.9904769024796283E+03; const nl_double k2 = 1.2070059213983407E+03; const nl_double k3 = 1.3266985579561108E+03; const nl_double k4 = -1.5500979825922698E+02; const nl_double k5 = 2.8184536266938172E+00; const nl_double k6 = -2.3503421582744556E+02; const nl_double k7 = -3.3836786704527788E+02; const nl_double k8 = -1.3569136703258670E+02; const nl_double k9 = 2.9914575453819188E+00; const nl_double k10 = 1.6855569086173170E+00; /* scale due to input resistance */ /* Polyfunctional3D_model created by zunzun.com using sum of squared absolute error */ v_freq_2 = v_freq * v_freq; v_freq_3 = v_freq_2 * v_freq; v_freq_4 = v_freq_3 * v_freq; freq = k1; freq += k2 * v_freq; freq += k3 * v_freq_2; freq += k4 * v_freq_3; freq += k5 * v_freq_4; freq += k6 * v_rng; freq += k7 * v_rng * v_freq; freq += k8 * v_rng * v_freq_2; freq += k9 * v_rng * v_freq_3; freq += k10 * v_rng * v_freq_4; freq *= NL_FCONST(0.1e-6) / m_CAP; // FIXME: we need a possibility to remove entries from queue ... // or an exact model ... m_clock.m_inc = netlist_time::from_double(0.5 / (double) freq); //m_clock.update(); //NL_VERBOSE_OUT(("{1} {2} {3} {4}\n", name(), v_freq, v_rng, freq)); } if (!m_clock.m_enableq && INPLOGIC(m_ENQ)) { m_clock.m_enableq = 1; m_clock.m_out = m_clock.m_out ^ 1; OUTLOGIC(m_clock.m_Y, m_clock.m_out, netlist_time::from_nsec(1)); } else if (m_clock.m_enableq && !INPLOGIC(m_ENQ)) { m_clock.m_enableq = 0; m_clock.m_out = m_clock.m_out ^ 1; OUTLOGIC(m_clock.m_Y, m_clock.m_out, netlist_time::from_nsec(1)); } } NETLIB_UPDATE_PARAM(SN74LS629) { update_dev(); } NETLIB_START(SN74LS629_dip) { register_sub("1", m_1); register_sub("2", m_2); register_subalias("1", m_2.m_FC); register_subalias("2", m_1.m_FC); register_subalias("3", m_1.m_RNG); register_subalias("6", m_1.m_ENQ); register_subalias("7", m_1.m_clock.m_Y); register_subalias("8", m_1.m_R_FC.m_N); register_subalias("9", m_1.m_R_FC.m_N); connect_late(m_1.m_R_FC.m_N, m_2.m_R_FC.m_N); register_subalias("10", m_2.m_clock.m_Y); register_subalias("11", m_2.m_ENQ); register_subalias("14", m_2.m_RNG); } NETLIB_UPDATE(SN74LS629_dip) { } NETLIB_RESET(SN74LS629_dip) { m_1.do_reset(); m_2.do_reset(); } NETLIB_NAMESPACE_DEVICES_END()