Revision 1:bb2b1e4bfb6e, committed 2016-03-05

Comitter:

MACRUM

Date:

Sat Mar 05 14:05:39 2016 +0000

Parent:

0:5a552209903c

Child:

2:4939ff09bf12

Commit message:

Add write protect functions and more comments

Changed in this revision

--- a/FM25W256.cpp	Fri Mar 04 15:49:51 2016 +0000
+++ b/FM25W256.cpp	Sat Mar 05 14:05:39 2016 +0000
@@ -1,3 +1,28 @@
+/* Cypress FM25W256 F-RAM component library
+ *
+ * Copyright (c) 2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *  *
+ *  @author  Toyomasa Watarai
+ *  @version 1.0
+ *  @date    5-March-2016
+ *
+ *  http://www.cypress.com/products/nonvolatile-ram
+ *  http://www.cypress.com/documentation/datasheets/fm25w256-256-kbit-32-k-8-serial-spi-f-ram?source=search&keywords=FM25W256&cat=technical_documents
+ *
+ */
+
 #include "mbed.h"
 #include "FM25W256.h"
 
@@ -5,17 +30,18 @@
     : _spi(mosi, miso, clk), _cs(cs)
 {
     _spi.format(8, 0);
-    _spi.frequency(20000000);
+    _spi.frequency(FM25W256_CLK);
     _cs = 1;
+    wait_ms(1); // tPU = 1ms (min.)
 }
 
 FM25W256::FM25W256(SPI &spi, PinName cs)
     : _spi(spi), _cs(cs) 
 {
     _spi.format(8, 0);
-    _spi.frequency(20000000);
+    _spi.frequency(FM25W256_CLK);
     _cs = 1;
-
+    wait_ms(1); // tPU = 1ms (min.)
 }
 
 void FM25W256::write(uint16_t address, uint8_t data)
@@ -73,3 +99,38 @@
     }
     _cs = 1;
 }
+
+void FM25W256::wirte_status(uint8_t data)
+{
+    _cs = 0;
+    _spi.write(CMD_WREN);
+    _cs = 1;
+
+    _cs = 0;
+    _spi.write(CMD_WRSR);
+    _spi.write(data);
+    _cs = 1;
+}
+
+uint8_t FM25W256::read_status()
+{
+    uint8_t data;
+    _cs = 0;
+    _spi.write(CMD_RDSR);
+    data = _spi.write(0);
+    _cs = 1;
+    
+    return data;
+}
+
+void FM25W256::set_write_protect(E_WP bp)
+{
+    // Set WPEN, BP0 and BP1
+    wirte_status((1 << 7) | (bp << 2));
+}
+
+void FM25W256::clear_write_protect()
+{
+    wirte_status(0);
+}
+    
\ No newline at end of file

--- a/FM25W256.h	Fri Mar 04 15:49:51 2016 +0000
+++ b/FM25W256.h	Sat Mar 05 14:05:39 2016 +0000
@@ -1,3 +1,28 @@
+/* Cypress FM25W256 F-RAM component library
+ *
+ * Copyright (c) 2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *  *
+ *  @author  Toyomasa Watarai
+ *  @version 1.0
+ *  @date    5-March-2016
+ *
+ *  http://www.cypress.com/products/nonvolatile-ram
+ *  http://www.cypress.com/documentation/datasheets/fm25w256-256-kbit-32-k-8-serial-spi-f-ram?source=search&keywords=FM25W256&cat=technical_documents
+ *
+ */
+ 
 #include "mbed.h"
 
 #ifndef __FM25W256_HEAD__
@@ -10,15 +35,112 @@
 #define CMD_READ   0x03
 #define CMD_WRITE  0x02
 
+#define FM25W256_CLK (20000000) // SPI clock 20MHz
+
+/** An interface for the Cypress 32k byte FM25W256 F-RAM over SPI
+
+@code
+#include "mbed.h"
+#include "FM25W256.h"
+
+Serial pc(USBTX, USBRX);
+FM25W256 f_ram(dp2, dp1, dp6, dp18);
+
+int main()
+{
+    uint8_t buf[16];
+    // Fill buffer
+    for(int i=0; i<16; i++) {
+        buf[i] = i;
+    }
+    // Write data to F-RAM
+    f_ram.write(0, buf, 16);
+
+    // Read data from F-RAM
+    uint16_t adrs = 0;
+    for(int i=0; i<16; i++) {
+        pc.printf("0x%04X : ", i * 16);
+        for(int j=0; j<16; j++) {
+            pc.printf("%02X ", f_ram.read(adrs++));
+        }
+        pc.printf("\n");
+    }
+    
+    while(1) {
+    }
+}
+*/
 class FM25W256 {
 public:
+
+    enum E_WP {
+        BANK_NONE = 0,
+        BANK_UPPER_QUARTER = 1,
+        BANK_UPPER_HALF = 2,
+        BANK_ALL = 3
+    };
+    
+/** Create an interface
+*
+* @param mosi  SPI master-out-slave-in
+* @param miso  SPI master-in-slave-out
+* @param clk   SPI clock
+* @param cs    chip select pin - any free Digital pin will do
+*/
     FM25W256(PinName mosi, PinName miso, PinName clk, PinName cs);
+
+/** Create an interface
+*
+* @param &spi  SPI instance
+* @param cs    chip select pin - any free Digital pin will do
+*/
     FM25W256(SPI &spi, PinName cs);
+    
+/** write a byte to F-RAM
+* @param address    The address F-RAM to write to
+* @param data       The byte to write there
+*/
     void write(uint16_t address, uint8_t data);
+
+/** write multiple bytes to F-RAM from a buffer
+* @param address    The F-RAM address write to
+* @param data       The buffer to write from
+* @param size       The number of bytes to write
+*/
     void write(uint16_t address, uint8_t *data, uint16_t size);
+
+/** read a byte from F-RAM
+* @param address    The address to read from
+* @return the character at that address
+*/
     uint8_t read(uint16_t address);
+
+/** read multiple bytes from F-RAM into a buffer
+* @param address    The F-RAM address to read from
+* @param data       The buffer to read into (must be big enough!)
+* @param size       The number of bytes to read
+*/
     void read(uint16_t address, uint8_t *data, uint16_t size);
 
+/** write a byte to the status register
+* @param data  The byte to write the register
+*/
+    void wirte_status(uint8_t data);
+
+/** read a byte from the status register
+* @return the character at the register
+*/
+    uint8_t read_status();
+
+/** Set write protect mode
+* @param bp   E_WP enum value
+*/
+    void set_write_protect(E_WP bp);
+
+/** Set write protect to non-protect mode
+*/
+    void clear_write_protect();
+
 protected:
     SPI _spi;
     DigitalOut _cs;