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-rw-r--r--avr/1wire.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/avr/1wire.c b/avr/1wire.c
index affd80d..54c8dcc 100644
--- a/avr/1wire.c
+++ b/avr/1wire.c
@@ -6,6 +6,30 @@
/* danni@specs.de */
/* */
/************************************************************************/
+
+/* modified by Florian Jung (flo@windfisch.org).
+ * Changelog:
+ * - try to drive parasite-powered devices via avr-builtin pullup
+ * - DS199X access functions
+ */
+
+/* WARNING WARNING WARNING:
+ * this code VIOLATES THE 1-WIRE SPECIFICATION! Instead of "letting the
+ * line float" (which implies that it's gently pulled up to 5V by the
+ * pullup resistor), we're hard connecting the line against +5V, without
+ * any resistor in between. After some time, we let the line float, only
+ * held up by the (weak) AVR-internal pullup.
+ *
+ * THIS COULD DESTROY YOUR HARDWARE! you have been warned.
+ *
+ * (We do this because the internal pullup isn't strong enough to serve
+ * the DS1992 with power. The line is only hard-connected to +5V, when
+ * we're (sort of) sure that the DS1992 won't pull down the line to GND
+ * (since that would cause a short-circuit). Buuuut there's no guarantee,
+ * it just works[tm])
+ */
+
+
#include <util/delay.h>
#include <avr/io.h>
#include <avr/interrupt.h>
@@ -176,6 +200,45 @@ void ds1992_read(uint16_t addr, uint8_t* buf, uint8_t len)
buf[i] = w1_byte_rd();
}
+void ds1992_scratch_write(uint16_t addr, const uint8_t* buf, uint8_t len)
+{
+ w1_byte_wr(SKIP_ROM);
+ w1_byte_wr(0x0F); // write scratchpad
+ w1_byte_wr((addr & 0x00FF));
+ w1_byte_wr((addr & 0xFF00) >> 8);
+ for (int i=0; i < len; i++)
+ w1_byte_wr(buf[i]);
+}
+
+uint8_t ds1992_scratch_verify(uint16_t addr, const uint8_t* buf, uint8_t len, uint8_t* es_reg_ptr)
+{
+ uint8_t status = 0;
+
+ w1_byte_wr(SKIP_ROM);
+ w1_byte_wr(0xAA); // read scratchpad
+
+ // check address bytes
+ if (w1_byte_rd() != (addr & 0x00FF)) status |= 0x01;
+ if (w1_byte_rd() != (addr & 0xFF00) >> 8) status |= 0x02;
+
+ uint8_t es_reg = w1_byte_rd();
+ *es_reg_ptr = es_reg;
+ // check E/S register
+ if (es_reg & 0x20) // PF: partial byte flag
+ status |= 0x04;
+ if (es_reg & 0x40) // OF: overflow flag
+ status |= 0x08;
+ if ((es_reg & 0x1F) != (addr & 0x1F) + (len-1))
+ status |= 0x10;
+
+ for (int i=0; i < len; i++)
+ if (w1_byte_rd() != buf[i])
+ status |= 0xF0;
+
+ return status;
+}
+
+
void w1_command( uint8_t command, uint8_t *id )
{
uint8_t i;