Diff: Drivers/DE0_driver.cpp

Revision:

0:a355e511bc5d

Child:

1:3e9684e81312

diff -r 000000000000 -r a355e511bc5d Drivers/DE0_driver.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Drivers/DE0_driver.cpp	Thu Feb 01 03:58:00 2018 +0000
@@ -0,0 +1,86 @@
+// DE0 FPGA driver
+
+#include "mbed.h"
+
+#define DUMMY   0
+
+SPI DE0(p5, p6, p7); // Configure pins and name SPI port.
+
+void ResetDE0(void);
+void RestartSpi(void);
+
+DigitalOut IoReset(p15);    // 0-1-0 reset for all SPI peripherals in the DE0 FPGA
+DigitalOut SpiReset(p14);   // 0-1-0 tells the DE0 SPI interace that the next word sent is a control word
+
+
+// To reset all SPI peripheral on the FPGA:
+void ResetDE0(void){
+    IoReset=0; // Reset all DE0 peripherals
+    IoReset=1;
+    wait_us(5);
+    IoReset=0; 
+    }
+   
+// To reset the SPI channel in the slave and restart with a new SPI protocol.    
+void RestartSpi(void) {
+    // Restart DE0 SPI channel so the next word sent is interpreted as the Control Word
+    SpiReset=0;
+    SpiReset=1;
+    wait_us(5);
+    SpiReset=0;
+    }
+
+void DE0_init(void)
+{
+ DE0.format(16,1); // Define SPI format: 16-bit words, mode 1 protocol.
+ DE0.frequency(500000); // Set SPI bit rate (Hz). Default is 1 MHz
+ ResetDE0();
+}
+
+/*
+
+Before an SPI data transaction with the DE0 FPGA can occur, a control word must 
+first be written to the slave that specifies: 
+
+i) the number of word transfers,
+ii) the offset or starting address within the slave, and 
+iii) whether the transaction consists of ‘simultaneous read write’ or whether the 
+transactions are ‘read only’ (from the slave). 
+
+A control word need only be written once – if the same transactions are repeated.
+Subsequent transactions use the protocol specified by the last control word that
+ was written. To change the transaction protocol a new control needs to be
+ written. To write a new control word, the SpiReset input must first be set then
+ cleared followed by a SPI write of a 16-bit word that is interpreted as the
+ control word by the slave.
+ 
+ The 16-bit control word format appears below.
+
+1        7bits            8bits
+rd | address offset | number of words 
+
+
+When RD = 1, no write operation occurs within the slave. Data on the MOSI is 
+ignored by the slave. When RD = 0, a simultaneous read + write of the slave 
+occurs.
+ 
+ */
+
+
+void DE0_read(uint16_t * id, uint16_t * dP, uint16_t * dT)
+{
+    // To place SPI module into control mode, where the next word received by the
+    // slave is interpreted as a control word.
+    RestartSpi();
+    
+    // rd = 1 (control if 1) address = 0 no of word = 2 - Specify a read only transactions of 2 words
+    *id = (uint16_t)DE0.write(0x8002);
+    
+    // Read the two 16 bits registers from the FPGA 
+    *dP = (uint16_t)DE0.write(DUMMY); // A SPI read only transaction occurs.
+    *dT = (uint16_t)DE0.write(DUMMY); //
+}
+
+ 
+
+    
\ No newline at end of file