diff --git a/.gitignore b/.gitignore
index 7226500..ab98bb0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,4 +24,5 @@ V203/usb/scope/software/moc/*
 V203/usb/scope/software/obj/*
 V203/usb/scope/software/qrc_src.cpp
 V203/usb/scope/software/ui_mainwindow.h
+V203/usb/spitest/*
 
diff --git a/V203/usb/ch32v203/spiclass.cpp b/V203/usb/ch32v203/spiclass.cpp
index 05885ec..e4fdcbf 100644
--- a/V203/usb/ch32v203/spiclass.cpp
+++ b/V203/usb/ch32v203/spiclass.cpp
@@ -82,14 +82,14 @@ void SpiClass::Init() {
     return r.R;
   }); 
   SPI1.CTLR1.modify([](SPI1_Type::CTLR1_DEF & r) -> uint32_t {
-    r.B.CPHA     = SET;
-    r.B.CPOL     = SET;
+    r.B.CPHA     = RESET;
+    r.B.CPOL     = RESET;
     r.B.MSTR     = SET;
     r.B.DFF      = RESET;     // 8 bit
     r.B.SSM      = SET;
     r.B.SSI      = SET;
-    r.B.LSBFIRST = RESET;
-    r.B.BR       = FPCLK_64;  // 4.5 MHz
+    r.B.LSBFIRST = SET;
+    r.B.BR       = FPCLK_32;  // 4.5 MHz
     return r.R;
   });
   SPI1.CTLR2.modify([](SPI1_Type::CTLR2_DEF & r) -> uint32_t {
@@ -106,6 +106,8 @@ bool SpiClass::send (const char * data, const unsigned int len) {
   complete = false;
   total    = len > SPIBUFLEN ? SPIBUFLEN : len;
   memcpy (buffer, data, total);
+  DMA1.PADDR3.R    = reinterpret_cast<size_t> (& SPI1.DATAR);
+  DMA1.MADDR3.R    = reinterpret_cast<size_t> (buffer);
   DMA1.CNTR3.R     = total;
   DMA1.CFGR3.B.EN  = SET;
   SPI1.CTLR1.B.SPE = SET;
diff --git a/V203/usb/ch32v203/spisim.cpp b/V203/usb/ch32v203/spisim.cpp
new file mode 100644
index 0000000..b639b8f
--- /dev/null
+++ b/V203/usb/ch32v203/spisim.cpp
@@ -0,0 +1,22 @@
+#include "spisim.h"
+#include "system.h"
+
+SpiSim::SpiSim() noexcept : nss(GPIOA,4), sck(GPIOA,5), mosi(GPIOA,7) {
+  delay_init();
+  nss  << true;
+  sck  << false;
+  mosi << false;
+}
+void SpiSim::outbyte(const uint8_t b) const {
+  nss << false;
+  for (unsigned n=0u; n<8; n++) {
+    const bool bit = (b & (1u << n)) ? true : false;
+    mosi << bit;
+    delay_us (2);
+    sck  << true;
+    delay_us (4);
+    sck  << false;
+    delay_us (2);
+  }
+  nss << true;
+}
diff --git a/V203/usb/ch32v203/spisim.h b/V203/usb/ch32v203/spisim.h
new file mode 100644
index 0000000..ddb843b
--- /dev/null
+++ b/V203/usb/ch32v203/spisim.h
@@ -0,0 +1,17 @@
+#ifndef SPISIM_H
+#define SPISIM_H
+#include "gpio.h"
+
+/** Původní třída SpiClass s DMA a hardware SPI se chová divně
+ * a je zbytečně složitá. Zde je potřeba odeslat 1 Byte na obvod
+ * 74595 a je jednodušší to udělat softwarově. Výstup je sice
+ * blokující, ale ten byte je dost krátká doba, aby to nerušilo.
+ */
+class SpiSim {
+  GpioClass nss, sck, mosi;
+  public:
+    explicit SpiSim  () noexcept;
+    void     outbyte (const uint8_t b) const;
+};
+
+#endif // SPISIM_H
diff --git a/V203/usb/scope/firmware/Makefile b/V203/usb/scope/firmware/Makefile
index 3b5399e..bd2c67c 100644
--- a/V203/usb/scope/firmware/Makefile
+++ b/V203/usb/scope/firmware/Makefile
@@ -17,7 +17,7 @@ DEL    = rm -f
 
 # zdrojaky
 OBJS   = main.o hack.o
-OBJS  += usb_desc.o cdc_class.o spiclass.o adcscope.o samplering.o
+OBJS  += usb_desc.o cdc_class.o spisim.o adcscope.o samplering.o
 
 include $(TARGET)/$(TOOL).mk
 BOBJS = $(addprefix $(BLD),$(OBJS))
diff --git a/V203/usb/scope/firmware/samplering.cpp b/V203/usb/scope/firmware/samplering.cpp
index a8e490a..639d5bd 100644
--- a/V203/usb/scope/firmware/samplering.cpp
+++ b/V203/usb/scope/firmware/samplering.cpp
@@ -76,11 +76,11 @@ void SampleRing::CommandPass(const unsigned int cmd) {
   switch (dest) {
     case DEST_CHA:
       voltage.a = header.bits.cmd_value;
-      spi.send (voltage.common, 1);
+      spi.outbyte (voltage.common[0]);
       break;
     case DEST_CHB:
       voltage.b = header.bits.cmd_value;
-      spi.send (voltage.common, 1);
+      spi.outbyte (voltage.common[0]);
       break;
     case DEST_BASE:
       m_time_base_order = header.bits.cmd_value;
diff --git a/V203/usb/scope/firmware/samplering.h b/V203/usb/scope/firmware/samplering.h
index 53581bf..a92873a 100644
--- a/V203/usb/scope/firmware/samplering.h
+++ b/V203/usb/scope/firmware/samplering.h
@@ -3,7 +3,7 @@
 #include <stdint.h>
 #include "structures.h"
 #include "baselayer.h"
-#include "spiclass.h"
+#include "spisim.h"
 
 static constexpr unsigned RING_BIT = 10;
 static constexpr unsigned RING_LEN = 1u << RING_BIT;
@@ -19,7 +19,7 @@ enum RCVD_STATUS {
 };
 
 class SampleRing : public BaseLayer {
-  SpiClass                      spi;
+  SpiSim                        spi;
   ChannelVoltage                voltage;
   [[gnu::aligned(4)]]DATA_BLOCK ring_buffer [RING_LEN];
   TrigerSettings                m_settings;
@@ -38,7 +38,7 @@ class SampleRing : public BaseLayer {
     explicit SampleRing () noexcept : BaseLayer(), spi(), voltage(), m_settings(), m_head(0), m_tail(0), m_lenght(0),
                                      m_old_triger(false), m_trigered(false), m_finished(false),
                                      m_mode (TIME_BASE_TRIGERED), o_mode (TIME_BASE_TRIGERED), m_time_base_order(6u),
-                                     rcvd_counter(0u), rcvd_status (RCVD_IDLE) { spi.Init(); };
+                                     rcvd_counter(0u), rcvd_status (RCVD_IDLE) { };
     uint32_t Up (const char * data, const uint32_t len) override;
     void write  (DATA_BLOCK const * data);
     void pass   ();