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/*
* Copyright © 2012 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; version 2 of the License.
*
* 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 <ao.h>
#include <ao_mma655x.h>
#if HAS_MMA655X
static uint8_t mma655x_configured;
static void
ao_mma655x_start(void) {
ao_spi_get_bit(AO_MMA655X_CS_GPIO,
AO_MMA655X_CS,
AO_MMA655X_CS_PIN,
AO_MMA655X_SPI_INDEX,
AO_SPI_SPEED_FAST);
}
static void
ao_mma655x_stop(void) {
ao_spi_put_bit(AO_MMA655X_CS_GPIO,
AO_MMA655X_CS,
AO_MMA655X_CS_PIN,
AO_MMA655X_SPI_INDEX);
}
static uint8_t
ao_parity(uint8_t v)
{
/* down to four bits */
v = (v ^ (v >> 4)) & 0xf;
/* Cute lookup hack -- 0x6996 encodes the sixteen
* even parity values in order.
*/
return (~0x6996 >> v) & 1;
}
static void
ao_mma655x_cmd(uint8_t d[2])
{
ao_mma655x_start();
ao_spi_send(d, 2, AO_MMA655X_SPI_INDEX);
ao_spi_recv(d, 2, AO_MMA655X_SPI_INDEX);
ao_mma655x_stop();
}
static uint8_t
ao_mma655x_reg_write(uint8_t addr, uint8_t value)
{
uint8_t d[2];
addr |= (1 << 6); /* write mode */
d[0] = addr | (ao_parity(addr^value) << 7);
d[1] = value;
ao_mma655x_cmd(d);
return d[1];
}
static uint8_t
ao_mma655x_reg_read(uint8_t addr)
{
uint8_t d[2];
d[0] = addr | (ao_parity(addr) << 7);
d[1] = 0;
ao_mma655x_cmd(d);
return d[1];
}
static uint16_t
ao_mma655x_value(void)
{
uint8_t d[2];
uint16_t v;
d[0] = ((0 << 7) | /* Axis selection (X) */
(1 << 6) | /* Acceleration operation */
(1 << 5)); /* Raw data */
d[1] = ((1 << 3) | /* must be one */
(1 << 2) | /* Unsigned data */
(0 << 1) | /* Arm disabled */
(1 << 0)); /* Odd parity */
ao_mma655x_cmd(d);
v = (uint16_t) d[1] << 2;
v |= d[0] >> 6;
v |= (uint16_t) (d[0] & 3) << 10;
return v;
}
static void
ao_mma655x_reset(void) {
ao_mma655x_reg_write(AO_MMA655X_DEVCTL,
(0 << AO_MMA655X_DEVCTL_RES_1) |
(0 << AO_MMA655X_DEVCTL_RES_1));
ao_mma655x_reg_write(AO_MMA655X_DEVCTL,
(1 << AO_MMA655X_DEVCTL_RES_1) |
(1 << AO_MMA655X_DEVCTL_RES_1));
ao_mma655x_reg_write(AO_MMA655X_DEVCTL,
(0 << AO_MMA655X_DEVCTL_RES_1) |
(1 << AO_MMA655X_DEVCTL_RES_1));
}
#define DEVCFG_VALUE (\
(1 << AO_MMA655X_DEVCFG_OC) | /* Disable offset cancelation */ \
(1 << AO_MMA655X_DEVCFG_SD) | /* Receive unsigned data */ \
(0 << AO_MMA655X_DEVCFG_OFMON) | /* Disable offset monitor */ \
(AO_MMA655X_DEVCFG_A_CFG_DISABLE << AO_MMA655X_DEVCFG_A_CFG))
#define AXISCFG_VALUE (\
(0 << AO_MMA655X_AXISCFG_LPF)) /* 100Hz 4-pole filter */
static void
ao_mma655x_setup(void)
{
uint8_t v;
uint16_t a, a_st;
uint8_t stdefl;
if (mma655x_configured)
return;
mma655x_configured = 1;
ao_delay(AO_MS_TO_TICKS(10)); /* Top */
ao_mma655x_reset();
ao_delay(AO_MS_TO_TICKS(10)); /* Top */
(void) ao_mma655x_reg_read(AO_MMA655X_DEVSTAT);
v = ao_mma655x_reg_read(AO_MMA655X_DEVSTAT);
/* Configure R/W register values.
* Most of them relate to the arming feature, which
* we don't use, so the only registers we need to
* write are DEVCFG and AXISCFG
*/
ao_mma655x_reg_write(AO_MMA655X_DEVCFG,
DEVCFG_VALUE | (0 << AO_MMA655X_DEVCFG_ENDINIT));
/* Test X axis
*/
ao_mma655x_reg_write(AO_MMA655X_AXISCFG,
AXISCFG_VALUE |
(1 << AO_MMA655X_AXISCFG_ST));
a_st = ao_mma655x_value();
stdefl = ao_mma655x_reg_read(AO_MMA655X_STDEFL);
ao_mma655x_reg_write(AO_MMA655X_AXISCFG,
AXISCFG_VALUE |
(0 << AO_MMA655X_AXISCFG_ST));
a = ao_mma655x_value();
printf ("normal: %u self_test: %u stdefl: %u\n",
a, a_st, stdefl);
ao_mma655x_reg_write(AO_MMA655X_DEVCFG,
DEVCFG_VALUE | (1 << AO_MMA655X_DEVCFG_ENDINIT));
}
static void
ao_mma655x_dump(void)
{
uint8_t s0, s1, s2, s3;
uint32_t lot;
uint16_t serial;
ao_mma655x_setup();
s0 = ao_mma655x_reg_read(AO_MMA655X_SN0);
s1 = ao_mma655x_reg_read(AO_MMA655X_SN1);
s2 = ao_mma655x_reg_read(AO_MMA655X_SN2);
s3 = ao_mma655x_reg_read(AO_MMA655X_SN3);
lot = ((uint32_t) s3 << 24) | ((uint32_t) s2 << 16) |
((uint32_t) s1 << 8) | ((uint32_t) s0);
serial = lot & 0x1fff;
lot >>= 12;
printf ("MMA655X lot %d serial %d\n", lot, serial);
mma655x_configured = 0;
}
__code struct ao_cmds ao_mma655x_cmds[] = {
{ ao_mma655x_dump, "A\0Display MMA655X data" },
{ 0, NULL },
};
static void
ao_mma655x(void)
{
ao_mma655x_setup();
for (;;) {
ao_data_ring[ao_data_head].mma655x = ao_mma655x_value();
ao_arch_critical(
AO_DATA_PRESENT(AO_DATA_MMA655X);
AO_DATA_WAIT();
);
}
}
static __xdata struct ao_task ao_mma655x_task;
void
ao_mma655x_init(void)
{
mma655x_configured = 0;
ao_cmd_register(&ao_mma655x_cmds[0]);
ao_spi_init_cs(AO_MMA655X_CS_GPIO, (1 << AO_MMA655X_CS));
ao_add_task(&ao_mma655x_task, ao_mma655x, "mma655x");
}
#endif
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