Add FRAM driver

libs/i2c-fram/fram.ts

@@ -0,0 +1,54 @@
+namespace i2c_fram {
+    const devaddr = 0x50;
+
+    //% shim=ksrt::panic
+    function panic(code: number) { }
+
+    function die() { panic(142) }
+
+    export function readByte(addr: number) {
+        if (addr < 0 || addr > 0xffff)
+            die();
+
+        let buf = pins.createBuffer(2)
+        buf[0] = (addr >> 8) & 0xff;
+        buf[1] = addr & 0xff;
+
+        pins.i2cWriteBuffer(devaddr, buf);
+        buf = pins.i2cReadBuffer(devaddr, 1);
+
+        return buf[0];
+    }
+
+    export function writeByte(addr: number, val: number) {
+        if (addr < 0 || addr > 0xffff)
+            die();
+
+        if (val < 0 || val > 0xff)
+            die();
+
+        let buf = pins.createBuffer(3)
+
+        buf[0] = (addr >> 8) & 0xff;
+        buf[1] = addr & 0xff;
+        buf[2] = val;
+
+        pins.i2cWriteBuffer(devaddr, buf)
+    }
+    
+    export function readBuffer(addr: number, length: number) {
+        if (addr < 0 || length < 0 || (addr + length) > 0xffff)
+            die();
+        let buf = pins.createBuffer(length)
+        for (let i = 0; i < length; ++i)
+            buf[i] = readByte(addr + i)
+        return buf
+    }
+    
+    export function writeBuffer(addr:number, buf: Buffer) {        
+        if (addr < 0 || (addr + buf.length) > 0xffff)
+            die();
+        for (let i = 0; i < buf.length; ++i)
+            writeByte(addr + i, buf[i])
+    }
+}