diff --git a/hwdefs.h b/hwdefs.h
index 195cf77..3b4cc76 100644
--- a/hwdefs.h
+++ b/hwdefs.h
@@ -55,7 +55,7 @@
 /****************************************************************************
 * RPi pico specific defs.
 ****************************************************************************/
-#define CLK_FREQ 48000000L                     /* pico's ADC clock is 48M. */
+#define CLK_ADC_FREQ 48000000L                 /* pico's ADC clock is 48M. */
 #define GPIO(x) (x)                        /* pico GPIO number to address. */
 #define PLL_SYS_MHZ 250                                   /* system clock. */
 
diff --git a/piodco/dco.pio b/piodco/dco.pio
index 03c2cdb..c472db8 100644
--- a/piodco/dco.pio
+++ b/piodco/dco.pio
@@ -1,17 +1,36 @@
 .program dco
+    set x, 0
+
 
 .wrap_target
+    pull ifempty    //                                              1
+    out y, 8        // load 8-bit delay value in terms of cycles.   2
+LOOP0:
+    jmp y-- LOOP0   // do accurate delay.                           3+t
+    set pins, 1     // set pins = 1.                                4+t.
 
-    out x, 8        // load 8-bit delay value in terms of cycles.   1
-LOOPH:
-    jmp x-- LOOPH   // do accurate delay.                           2+x
-    set pins, 1     // set pins = 1.                                3+x.
 
-    out x, 8        // load 8-bit delay value in terms of cycles.   4+y
-LOOPL:
-    jmp x-- LOOPL   //                                              5+y
-    set pins, 0     //                                              6+y
-                    // CLK/6 max, ~250MHz/6 = 41.666(6)MHz output max frq
+    pull ifempty    //                                              5+t
+    out y, 8        // load 8-bit delay value in terms of cycles.   6+t
+LOOP1:
+    jmp y-- LOOP1   //                                              7+t
+    set pins, 0     //                                              8+t
+                    // CLK/8 max, 250MHz/8 = 31.25 MHz output max frq.
+                    // CLK/(255+8) min, 250MHz/263 = 950 kHz min frq.
+                    // So, it covers 3..30 MHz HF band + 160 meter band.
+    pull ifempty
+    out y, 8
+LOOP2:
+    jmp y-- LOOP2
+    set pins, 1
+
+
+    pull ifempty
+    out y, 8
+LOOP3:
+    jmp y-- LOOP3
+    set pins, 0
+
 .wrap
 
 % c-sdk {
@@ -21,7 +40,7 @@ static inline void dco_program_init(PIO pio, uint sm, uint offset, uint pin)
     sm_config_set_out_pins(&c, pin, 1);
     pio_gpio_init(pio, pin);
 
-    sm_config_set_out_shift(&c, false, true, 32);
+    sm_config_set_out_shift(&c, false, true, 8);           // Autopull.
     sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
 
     pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
@@ -34,14 +53,14 @@ static inline void dco_program_init(PIO pio, uint sm, uint offset, uint pin)
 //
 static inline void dco_program_puts(PIO pio, uint sm, const uint32_t *s)
 {
-    pio_sm_put(pio, sm, s[0]);
-    pio_sm_put(pio, sm, s[1]);
-    pio_sm_put(pio, sm, s[2]);
-    pio_sm_put(pio, sm, s[3]);
-    pio_sm_put(pio, sm, s[4]);
-    pio_sm_put(pio, sm, s[5]);
-    pio_sm_put(pio, sm, s[6]);
-    pio_sm_put(pio, sm, s[7]);
+    pio_sm_put_blocking(pio, sm, s[0]);
+    pio_sm_put_blocking(pio, sm, s[1]);
+    pio_sm_put_blocking(pio, sm, s[2]);
+    pio_sm_put_blocking(pio, sm, s[3]);
+    pio_sm_put_blocking(pio, sm, s[4]);
+    pio_sm_put_blocking(pio, sm, s[5]);
+    pio_sm_put_blocking(pio, sm, s[6]);
+    pio_sm_put_blocking(pio, sm, s[7]);
 }
 
 %}
diff --git a/piodco/piodco.c b/piodco/piodco.c
index 531945f..58b105f 100644
--- a/piodco/piodco.c
+++ b/piodco/piodco.c
@@ -3,18 +3,32 @@
 #include <string.h>
 #include "../lib/assert.h"
 
-int PioDCOInit(piodco *pdco, uint32_t ui32_clock_hz)
+#include "build/dco.pio.h"
+
+int PioDCOInit(PioDco *pdco, uint32_t ui32_clock_hz)
 {
     assert_(pdco);
 
-    memset(pdco, 0, sizeof(piodco));
+    memset(pdco, 0, sizeof(PioDco));
 
     pdco->_clkfreq_hz = ui32_clock_hz;
+    pdco->_pio = pio0;
+    pdco->_gpio = 6;
+    pdco->_offset = pio_add_program(pdco->_pio, &dco_program);
+    pdco->_ism = pio_claim_unused_sm(pdco->_pio, true);
+
+    dco_program_init(pdco->_pio, pdco->_ism, pdco->_offset, pdco->_gpio);
+    pdco->_pio_sm = dco_program_get_default_config(pdco->_offset);
+
+    sm_config_set_set_pins(&pdco->_pio_sm, pdco->_gpio, 1);
+    pio_gpio_init(pdco->_pio, pdco->_gpio);
+    pio_sm_init(pdco->_pio, pdco->_ism, pdco->_offset, &pdco->_pio_sm);
+    pio_sm_set_enabled(pdco->_pio, pdco->_ism, true);
 
     return 0;
 }
 
-int PioDCOSet(piodco *pdco, uint32_t ui32_frq_hz)
+int PioDCOSet(PioDco *pdco, uint32_t ui32_frq_hz)
 {
     assert_(pdco);
     assert(pdco->_clkfreq_hz);
@@ -27,17 +41,17 @@ int PioDCOSet(piodco *pdco, uint32_t ui32_frq_hz)
     return 0;
 }
 
-void PioDCOStart(piodco *pdco)
+void PioDCOStart(PioDco *pdco)
 {
 
 }
 
-void PioDCOStop(piodco *pdco)
+void PioDCOStop(PioDco *pdco)
 {
 
 }
 
-void PioDCOTick(piodco *pdco)
+void PioDCOTick(PioDco *pdco)
 {
 
 }
diff --git a/piodco/piodco.h b/piodco/piodco.h
index e620ca4..c828888 100644
--- a/piodco/piodco.h
+++ b/piodco/piodco.h
@@ -6,32 +6,30 @@
 #include "pico/stdlib.h"
 #include "hardware/pio.h"
 
-
 typedef struct
 {
-    //bool _brun;
-
     PIO _pio;                   /* Worker PIO on this DCO. */
     int _gpio;                  /* Pico' GPIO for DCO output. */
 
     pio_sm_config _pio_sm;      /* Worker PIO parameter. */
+    int _ism;                   /* Index of state maschine. */
     int _offset;                /* Worker PIO u-program offset. */
 
     uint32_t _phase_prompt;     /* Last DCO phase val, [0...2PI). */
     uint32_t _phase_increment;  /* DCO phase increment, per 1 CLK. */
 
-    uint32_t _ui32_pioreg[8];   /* Shift register into PIO. */
+    uint32_t _ui32_pioreg[8];   /* Shift register to PIO. */
 
     uint32_t _clkfreq_hz;       /* CPU CLK freq, Hz. */
 
-} piodco;
+} PioDco;
 
-int PioDCOInit(piodco *pdco, uint32_t ui32_clock_hz);
-int PioDCOSet(piodco *pdco, uint32_t ui32_frq_hz);
+int PioDCOInit(PioDco *pdco, uint32_t ui32_clock_hz);
+int PioDCOSet(PioDco *pdco, uint32_t ui32_frq_hz);
 
-void PioDCOStart(piodco *pdco);
-void PioDCOStop(piodco *pdco);
+void PioDCOStart(PioDco *pdco);
+void PioDCOStop(PioDco *pdco);
 
-void PioDCOTick(piodco *pdco);
+void PioDCOTick(PioDco *pdco);
 
 #endif
diff --git a/test.c b/test.c
index 821ccfb..4321fc5 100644
--- a/test.c
+++ b/test.c
@@ -5,14 +5,35 @@
 #include "build/dco.pio.h"
 #include "hardware/vreg.h"
 
+#include "./lib/assert.h"
+#include "hwdefs.h"
+#include "./dcoisr/dcoisr.h"
+
 int main() 
 {
-    //vreg_set_voltage(VREG_VOLTAGE_1_25);
-    set_sys_clock_khz(270000, true);
+    PioDco DCO;
+    DcoIsrContext ISRC;
+
+    set_sys_clock_khz(PLL_SYS_MHZ * 1000L, true);
 
     gpio_init(PICO_DEFAULT_LED_PIN);
     gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT);
 
+    assert_(0 == PioDCOInit(&DCO, PLL_SYS_MHZ * 1000000L));  
+    //DcoIsrInit(&ISRC, &DCO);
+
+    uint32_t pval[8];
+    memset((char *)pval, 0x00, 32);
+    for(;;)
+    {
+        gpio_put(PICO_DEFAULT_LED_PIN, 0);
+        dco_program_puts(DCO._pio, DCO._ism, pval);
+        
+        gpio_put(PICO_DEFAULT_LED_PIN, 1);
+        dco_program_puts(DCO._pio, DCO._ism, pval);
+    }
+
+/*
     const int offset = pio_add_program(pio0, &dco_program);
     const int ism = pio_claim_unused_sm(pio0, true);
 
@@ -37,6 +58,7 @@ int main()
         gpio_put(PICO_DEFAULT_LED_PIN, 0);
         //sleep_ms(1000);
     }
+    */
 /*
     pcb->c = bitdco_program_get_default_config(offset);
     pcb->pio = pio;