Update hspi_slave.c

I found that SPI communication did not work due te a wrong timing of the MISO signal with respect to SCK. With slower processores like Arduino UNO (and a small delay of sck due to th level converter) it works, but with a faster Arduino DUE (without converter) it did not. Together with Jiri Bilek I found that MISODM_S has to be set. In the documentation for the ESP32 (should have a very similar SPI interface) I found that also MOSIDN_S should be set in SPI1C2.  The MISO timing is correct, I tested it for a clock of 4 MHZ and 320 kHz. With experiments I found that also the timing of MOSI is robust. Neither a delay of 70 ns in SCK nor in MOSI did disturb the communication. Some oscillograms are here: http://homepage.o2mail.de/g.ackermann/hspi_slave.htm

Jiri Bilek added the ICACHE_RAM_ATTR to the function hspi_slave_setStatus() because this function may be indirect called from an interrupt handler.

libraries/SPISlave/src/hspi_slave.c

@@ -92,7 +92,7 @@ void hspi_slave_begin(uint8_t status_len, void * arg)
     SPI1S1 = (((status_len * 8) - 1) << SPIS1LSTA) | (0xff << SPIS1LBUF) | (7 << SPIS1LWBA) | (7 << SPIS1LRBA) | SPIS1RSTA;
     SPI1P = (1 << 19);
     SPI1CMD = SPIBUSY;
-
+    SPI1C2=(0x2<<SPIC2MOSIDN_S) | (0x1<<SPIC2MISODM_S); // GuaAck. 30.10.2018; timing of MISO 
     ETS_SPI_INTR_ATTACH(_hspi_slave_isr_handler,arg);
     ETS_SPI_INTR_ENABLE();
 }
@@ -114,7 +114,7 @@ void hspi_slave_end()
   SPI1P = B110;
 }
 
-void hspi_slave_setStatus(uint32_t status)
+void ICACHE_RAM_ATTR hspi_slave_setStatus(uint32_t status) // GuaAck. 30.10.2018
 {
     SPI1WS = status;
 }