--- /dev/null
+/*
+ * Copyright © 2008 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <stdint.h>
+
+sfr at 0x80 P0;
+sfr at 0x90 P1;
+sfr at 0xA0 P2;
+sfr at 0xC6 CLKCON;
+
+sfr at 0xF1 PERCFG;
+sfr at 0xF2 ADCCFG;
+sfr at 0xF3 P0SEL;
+sfr at 0xF4 P1SEL;
+sfr at 0xF5 P2SEL;
+
+sfr at 0xFD P0DIR;
+sfr at 0xFE P1DIR;
+sfr at 0xFF P2DIR;
+sfr at 0x8F P0INP;
+sfr at 0xF6 P1INP;
+sfr at 0xF7 P2INP;
+
+sfr at 0x89 P0IFG;
+sfr at 0x8A P1IFG;
+sfr at 0x8B P2IFG;
+
+sbit at 0x90 P1_0;
+sbit at 0x91 P1_1;
+sbit at 0x92 P1_2;
+sbit at 0x93 P1_3;
+sbit at 0x94 P1_4;
+sbit at 0x95 P1_5;
+sbit at 0x96 P1_6;
+sbit at 0x97 P1_7;
+
+#define MOSI P1_5
+#define MISO P1_4
+#define SCK P1_3
+#define CS P1_2
+
+#define DEBUG P1_1
+
+#define nop() _asm nop _endasm;
+
+void
+delay (unsigned char n)
+{
+ unsigned char i = 0;
+ unsigned char j = 0;
+
+ while (--n != 0)
+ while (--i != 0)
+ while (--j != 0)
+ nop();
+}
+
+void
+cs(uint8_t b)
+{
+ CS = b;
+ delay(1);
+}
+
+void
+out_bit(uint8_t b)
+{
+ MOSI = b;
+ SCK = 1;
+ delay(1);
+ SCK = 0;
+ delay(1);
+}
+
+void
+out_byte(uint8_t byte)
+{
+ uint8_t s;
+
+ for (s = 0; s < 8; s++) {
+ uint8_t b = (byte & 0x80) ? 1 : 0;
+ out_bit(b);
+ byte <<= 1;
+ }
+}
+
+uint8_t
+in_bit(void)
+{
+ uint8_t b;
+ SCK = 1;
+ delay(1);
+ b = MISO;
+ SCK = 0;
+ delay(1);
+ return b;
+}
+
+uint8_t
+in_byte(void)
+{
+ uint8_t byte = 0;
+ uint8_t s;
+ uint8_t b;
+
+ for (s = 0; s < 8; s++) {
+ b = in_bit();
+ byte = byte << 1;
+ byte |= s;
+ }
+ return byte;
+}
+
+uint8_t
+rdsr(void)
+{
+ uint8_t status;
+ cs(0);
+ out_byte(0x05);
+ status = in_byte();
+ cs(1);
+ return status;
+}
+
+void
+wrsr(uint8_t status)
+{
+ cs(0);
+ out_byte(0x01);
+ out_byte(status);
+ cs(1);
+}
+
+void
+wren(void)
+{
+ cs(0);
+ out_byte(0x06);
+ cs(1);
+}
+
+void
+write(uint32_t addr, uint8_t *bytes, uint16_t len)
+{
+ wren();
+ cs(0);
+ out_byte(0x02);
+ out_byte(addr >> 16);
+ out_byte(addr >> 8);
+ out_byte(addr);
+ while (len-- > 0)
+ out_byte(*bytes++);
+ cs(1);
+ for (;;) {
+ uint8_t status = rdsr();
+ if ((status & (1 << 0)) == 0)
+ break;
+ }
+}
+
+void
+read(uint32_t addr, uint8_t *bytes, uint16_t len)
+{
+ cs(0);
+ out_byte(0x03);
+ out_byte(addr >> 16);
+ out_byte(addr >> 8);
+ out_byte(addr);
+ while (len-- > 0)
+ *bytes++ = in_byte();
+ cs(1);
+}
+
+void
+debug_byte(uint8_t byte)
+{
+ uint8_t s;
+
+ for (s = 0; s < 8; s++) {
+ DEBUG = byte & 1;
+ delay(2);
+ byte >>= 1;
+ }
+}
+
+#define STRING "hi"
+#define LENGTH 2
+
+main ()
+{
+ uint8_t status;
+ uint8_t buf[LENGTH];
+ int i;
+
+ CLKCON = 0;
+
+ CS = 1;
+ SCK = 0;
+ P1DIR = ((1 << 5) |
+ (1 << 4) |
+ (1 << 3) |
+ (1 << 2) |
+ (1 << 1));
+ status = rdsr();
+ /*
+ * Turn off both block-protect bits
+ */
+ status &= ~((1 << 3) | (1 << 2));
+ /*
+ * Turn off write protect enable
+ */
+ status &= ~(1 << 7);
+ wrsr(status);
+ write(0x0, STRING, LENGTH);
+ for (;;) {
+ read(0x0, buf, LENGTH);
+ for (i = 0; i < LENGTH; i++)
+ debug_byte(buf[i]);
+ }
+}