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| /*
* Si4732-A10 AM/FM receiver demo — AVR128DA28, bare-metal, I2C mode.
*
* Single-file build: UART, TWI and the Si4732 driver are all included here.
*
* Pinout (same as the Si4703 demo so the board layout can be shared):
* PC0 USART1 TX (115200)
* PC1 USART1 RX
* PC2 TWI0 SDA → Si4732 SDIO 12
* PC3 TWI0 SCL → Si4732 SCLK 11
* PD0 GPIO out → Si4732 RST 9
* SEN tied LOW (default I2C address 0x11). With SEN tied HIGH the device
* answers on 0x63 — change SI4732_ADDR below.
*
* UART commands (115200 8N1):
* u/U freq +1 step (FM: +100 kHz, AM: +10 kHz)
* d/D freq -1 step
* S seek up
* s seek down
* + volume up
* - volume down
* m toggle mute
* F switch to FM (87.5–108 MHz)
* A switch to AM/MW (520–1710 kHz)
* W switch to SW 31m (9400–9900 kHz)
* 0 show status
* r show RDS (FM only)
* i show chip revision
* ? help
*
* Ported from the PU2CLR SI4735 Arduino library
* https://github.com/pu2clr/SI4735
* adapted to plain C and the AVR128DA TWI driver shared with the Si4703 demo.
*
* References:
* - Si4732-A10 datasheet
* - AN332 Si47xx Programming Guide
* §4.1 Powerup sequence (RST low, then I2C address selected by SEN)
* §4.2 Command / response framing over the 2-wire bus
* - AN383 Si47xx Antenna, schematic and layout
*/
#include <avr/io.h>
#include <util/delay.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
/* ============================================================================
* USART1 — 115200 8N1, PC0=TX, PC1=RX
* ========================================================================== */
static void UART1_init(void) {
PORTC.DIRSET = PIN0_bm;
PORTC.DIRCLR = PIN1_bm;
USART1.BAUD = (uint16_t)((64UL * F_CPU) / (16UL * 115200UL) + 0.5);
USART1.CTRLC = USART_CMODE_ASYNCHRONOUS_gc | USART_CHSIZE_8BIT_gc;
USART1.CTRLB = USART_TXEN_bm | USART_RXEN_bm;
}
static void UART1_write(char c) {
while (!(USART1.STATUS & USART_DREIF_bm));
USART1.TXDATAL = c;
}
static void UART1_send_string(const char *s) {
while (*s) UART1_write(*s++);
}
static bool UART1_rx_available(void) {
return (USART1.STATUS & USART_RXCIF_bm) != 0;
}
static char UART1_read(void) {
while (!(USART1.STATUS & USART_RXCIF_bm));
return (char)USART1.RXDATAL;
}
/* ============================================================================
* TWI0 master @ 100 kHz, ALT2 (PC2/PC3) at F_CPU=24 MHz
*
* Baudrate: MBAUD = F_CPU/(2*F_SCL) - 5 = 24M/(2*100k) - 5 = 115.
* ========================================================================== */
static void TWI0_init(void) {
PORTMUX.TWIROUTEA = 0x02; /* TWI0 → PC2/PC3 */
TWI0.CTRLA = TWI_SDAHOLD_50NS_gc;
TWI0.DUALCTRL = 0x00;
TWI0.DBGCTRL = TWI_DBGRUN_bm;
TWI0.MBAUD = 115;
TWI0.MSTATUS = TWI_RIF_bm | TWI_WIF_bm | TWI_CLKHOLD_bm |
TWI_RXACK_bm | TWI_ARBLOST_bm | TWI_BUSERR_bm |
TWI_BUSSTATE_IDLE_gc;
TWI0.MCTRLA = TWI_ENABLE_bm;
}
static bool TWI_write(uint8_t addr, const uint8_t *data, uint16_t len) {
TWI0.MADDR = (addr << 1) | 0;
for (uint16_t i = 0; i < len; i++) {
while (!(TWI0.MSTATUS & TWI_WIF_bm));
if (TWI0.MSTATUS & (TWI_ARBLOST_bm | TWI_BUSERR_bm)) return false;
if (TWI0.MSTATUS & TWI_RXACK_bm) return false;
TWI0.MDATA = data[i];
}
while (!(TWI0.MSTATUS & TWI_WIF_bm));
TWI0.MCTRLB = TWI_MCMD_STOP_gc;
return true;
}
static bool TWI_read(uint8_t addr, uint8_t *data, uint16_t len) {
TWI0.MADDR = (addr << 1) | 1;
for (uint16_t i = 0; i < len; i++) {
while (!(TWI0.MSTATUS & TWI_RIF_bm));
if (TWI0.MSTATUS & (TWI_ARBLOST_bm | TWI_BUSERR_bm)) return false;
data[i] = TWI0.MDATA;
if (i < (len - 1)) TWI0.MCTRLB = TWI_MCMD_RECVTRANS_gc;
else TWI0.MCTRLB = TWI_ACKACT_NACK_gc | TWI_MCMD_STOP_gc;
}
return true;
}
/* ============================================================================
* Si4732-A10 driver
*
* Frequency units used by this API:
* FM : 10 kHz steps (e.g. 9850 = 98.5 MHz)
* AM : 1 kHz steps (e.g. 810 = 810 kHz, 9650 = 9.650 MHz)
*
* Protocol notes:
* - Every command is N bytes [CMD, ARG1..ARGn]. The first response byte is
* the STATUS byte: bit 7 = CTS, bit 6 = ERR, bit 0 = STCINT.
* - After each command we wait for CTS=1 before issuing the next one. Tune
* completion is reported by STCINT in GET_INT_STATUS.
* - Frequencies sent to the chip are unsigned big-endian 16-bit values.
* FM tunes are in 10 kHz units, AM/SW tunes are in 1 kHz units.
* ========================================================================== */
typedef enum {
SI4732_MODE_FM = 0,
SI4732_MODE_AM = 1,
} si4732_mode_t;
#define SI4732_ADDR 0x11 /* SEN tied LOW (datasheet §6.2) */
/* Command opcodes (AN332 Table 4) */
#define CMD_POWER_UP 0x01
#define CMD_GET_REV 0x10
#define CMD_POWER_DOWN 0x11
#define CMD_SET_PROPERTY 0x12
#define CMD_GET_PROPERTY 0x13
#define CMD_GET_INT_STATUS 0x14
#define CMD_FM_TUNE_FREQ 0x20
#define CMD_FM_SEEK_START 0x21
#define CMD_FM_TUNE_STATUS 0x22
#define CMD_FM_RSQ_STATUS 0x23
#define CMD_FM_RDS_STATUS 0x24
#define CMD_AM_TUNE_FREQ 0x40
#define CMD_AM_SEEK_START 0x41
#define CMD_AM_TUNE_STATUS 0x42
#define CMD_AM_RSQ_STATUS 0x43
/* Properties (AN332 Table 9) */
#define PROP_GPO_IEN 0x0001
#define PROP_FM_DEEMPHASIS 0x1100
#define PROP_FM_RDS_INT_SOURCE 0x1500
#define PROP_FM_RDS_INT_FIFO_COUNT 0x1501
#define PROP_FM_RDS_CONFIG 0x1502
#define PROP_FM_SEEK_FREQ_SPACING 0x1102
#define PROP_AM_DEEMPHASIS 0x3100
#define PROP_AM_CHANNEL_FILTER 0x3102
#define PROP_AM_AUTOMATIC_VOLUME_CONTROL_MAX_GAIN 0x3103
#define PROP_AM_FRONTEND_AGC_CONTROL 0x3122
#define PROP_AM_SEEK_FREQ_SPACING 0x4102
#define PROP_RX_VOLUME 0x4000
#define PROP_RX_HARD_MUTE 0x4001
/* Status byte bits */
#define STATUS_CTS 0x80
#define STATUS_ERR 0x40
#define STATUS_RDSINT 0x04
#define STATUS_STCINT 0x01
/* Tune-status response flags */
#define TUNE_STATUS_BLTF 0x80 /* band limit reached */
#define TUNE_STATUS_VALID 0x01
#define FM_DEFAULT_BOTTOM 8750u /* 87.5 MHz */
#define FM_DEFAULT_TOP 10800u /* 108.0 MHz */
#define FM_DEFAULT_SPACING 10u /* 100 kHz */
#define AM_DEFAULT_BOTTOM 520u
#define AM_DEFAULT_TOP 1710u
#define AM_DEFAULT_SPACING 10u /* 10 kHz MW grid */
static si4732_mode_t s_mode = SI4732_MODE_FM;
static uint16_t s_band_lo = FM_DEFAULT_BOTTOM;
static uint16_t s_band_hi = FM_DEFAULT_TOP;
static uint16_t s_spacing = FM_DEFAULT_SPACING;
static uint16_t s_freq = 0;
static uint8_t s_rssi = 0;
static uint8_t s_snr = 0;
static bool s_stereo = false;
static uint8_t s_volume = 32;
static char rds_ps[9];
static char rds_rt[65];
static int8_t rds_rt_ab = -1;
static bool rds_sync = false;
/* -------- Low-level command / response --------------------------------- */
/* Wait until STATUS.CTS=1. Each read fetches a single status byte. */
static bool wait_cts(uint16_t timeout_ms) {
uint8_t status = 0;
for (uint16_t t = 0; t < timeout_ms; t++) {
if (TWI_read(SI4732_ADDR, &status, 1) && (status & STATUS_CTS)) return true;
_delay_ms(1);
}
return false;
}
static bool send_cmd(const uint8_t *buf, uint8_t len) {
if (!TWI_write(SI4732_ADDR, buf, len)) return false;
return wait_cts(500);
}
/* Send a command then read a multi-byte response (status byte included). */
static bool send_cmd_read(const uint8_t *cmd, uint8_t clen,
uint8_t *resp, uint8_t rlen) {
if (!send_cmd(cmd, clen)) return false;
return TWI_read(SI4732_ADDR, resp, rlen);
}
static bool set_property(uint16_t prop, uint16_t value) {
uint8_t buf[6] = {
CMD_SET_PROPERTY,
0x00,
(uint8_t)(prop >> 8), (uint8_t)(prop & 0xFF),
(uint8_t)(value >> 8), (uint8_t)(value & 0xFF),
};
if (!send_cmd(buf, 6)) return false;
_delay_ms(1);
return true;
}
static bool get_int_status(uint8_t *status_byte) {
uint8_t cmd = CMD_GET_INT_STATUS;
if (!TWI_write(SI4732_ADDR, &cmd, 1)) return false;
if (!wait_cts(50)) return false;
return TWI_read(SI4732_ADDR, status_byte, 1);
}
/* -------- Powerup / mode ------------------------------------------------ */
static void hw_reset(void) {
PORTD.DIRSET = PIN0_bm;
PORTD.OUTCLR = PIN0_bm;
_delay_ms(10);
PORTD.OUTSET = PIN0_bm;
_delay_ms(10);
}
static bool power_up(si4732_mode_t mode) {
/* ARG1: CTSIEN=0, GPO2OEN=0, PATCH=0, XOSCEN=1, FUNC = mode (0=FM, 1=AM)
* ARG2: OPMODE = 0x05 (analog audio out, L+R) */
uint8_t func = (mode == SI4732_MODE_FM) ? 0x00 : 0x01;
uint8_t buf[3] = { CMD_POWER_UP, (uint8_t)(0x10 | func), 0x05 };
if (!send_cmd(buf, 3)) return false;
_delay_ms(110); /* AN332 §4.1: ≥110 ms after powerup */
return true;
}
static bool power_down(void) {
uint8_t cmd = CMD_POWER_DOWN;
if (!send_cmd(&cmd, 1)) return false;
_delay_ms(10);
return true;
}
static void rds_clear(void) {
for (uint8_t i = 0; i < 8; i++) rds_ps[i] = ' ';
rds_ps[8] = '\0';
for (uint8_t i = 0; i < 64; i++) rds_rt[i] = ' ';
rds_rt[64] = '\0';
rds_rt_ab = -1;
rds_sync = false;
}
static void apply_band_defaults(si4732_mode_t mode) {
if (mode == SI4732_MODE_FM) {
s_band_lo = FM_DEFAULT_BOTTOM;
s_band_hi = FM_DEFAULT_TOP;
s_spacing = FM_DEFAULT_SPACING;
} else {
s_band_lo = AM_DEFAULT_BOTTOM;
s_band_hi = AM_DEFAULT_TOP;
s_spacing = AM_DEFAULT_SPACING;
}
}
static bool configure_mode(si4732_mode_t mode) {
if (mode == SI4732_MODE_FM) {
set_property(PROP_FM_DEEMPHASIS, 0x0001); /* 50 us (EU) */
set_property(PROP_FM_SEEK_FREQ_SPACING, 10); /* 100 kHz */
set_property(PROP_FM_RDS_CONFIG, 0xAA01); /* RDSEN=1, blk-err thr */
set_property(PROP_FM_RDS_INT_SOURCE, 0x0001); /* RDSRECV */
set_property(PROP_FM_RDS_INT_FIFO_COUNT, 4);
} else {
set_property(PROP_AM_DEEMPHASIS, 0x0001);
set_property(PROP_AM_CHANNEL_FILTER, 0x0003); /* 4 kHz BW, AM */
set_property(PROP_AM_SEEK_FREQ_SPACING, s_spacing);
}
set_property(PROP_RX_HARD_MUTE, 0x0000);
return set_property(PROP_RX_VOLUME, s_volume);
}
static bool Si4732_init(si4732_mode_t mode) {
TWI0_init();
hw_reset();
rds_clear();
s_mode = mode;
apply_band_defaults(mode);
if (!power_up(mode)) return false;
if (!configure_mode(mode)) return false;
return true;
}
static bool Si4732_set_mode(si4732_mode_t mode) {
if (!power_down()) return false;
s_mode = mode;
apply_band_defaults(mode);
rds_clear();
if (!power_up(mode)) return false;
return configure_mode(mode);
}
static si4732_mode_t Si4732_mode(void) { return s_mode; }
static void Si4732_set_band(uint16_t bottom, uint16_t top, uint16_t spacing) {
s_band_lo = bottom;
s_band_hi = top;
s_spacing = spacing ? spacing : 1;
if (s_mode == SI4732_MODE_AM) {
set_property(PROP_AM_SEEK_FREQ_SPACING, s_spacing);
} else {
set_property(PROP_FM_SEEK_FREQ_SPACING, s_spacing);
}
}
/* -------- Tune / status ------------------------------------------------- */
static bool poll_stc(uint16_t timeout_ms) {
for (uint16_t t = 0; t < timeout_ms; t++) {
uint8_t status = 0;
if (get_int_status(&status) && (status & STATUS_STCINT)) return true;
_delay_ms(5);
}
return false;
}
static bool tune_status_fm(void) {
uint8_t cmd[2] = { CMD_FM_TUNE_STATUS, 0x01 }; /* INTACK=1 */
uint8_t resp[8] = { 0 };
if (!send_cmd_read(cmd, 2, resp, 8)) return false;
s_freq = ((uint16_t)resp[2] << 8) | resp[3];
s_rssi = resp[4];
s_snr = resp[5];
s_stereo = false; /* set by RSQ below */
uint8_t cmd2[2] = { CMD_FM_RSQ_STATUS, 0x01 };
uint8_t resp2[8] = { 0 };
if (send_cmd_read(cmd2, 2, resp2, 8)) {
s_stereo = (resp2[3] & 0x80) != 0; /* PILOT bit */
}
return true;
}
static bool tune_status_am(void) {
uint8_t cmd[2] = { CMD_AM_TUNE_STATUS, 0x01 };
uint8_t resp[8] = { 0 };
if (!send_cmd_read(cmd, 2, resp, 8)) return false;
s_freq = ((uint16_t)resp[2] << 8) | resp[3];
s_rssi = resp[4];
s_snr = resp[5];
s_stereo = false;
return true;
}
static bool Si4732_refresh(void) {
return (s_mode == SI4732_MODE_FM) ? tune_status_fm() : tune_status_am();
}
static bool Si4732_tune(uint16_t freq) {
rds_clear();
if (s_mode == SI4732_MODE_FM) {
uint8_t buf[5] = {
CMD_FM_TUNE_FREQ, 0x00,
(uint8_t)(freq >> 8), (uint8_t)(freq & 0xFF),
0x00, /* ANTCAP=auto */
};
if (!send_cmd(buf, 5)) return false;
} else {
uint8_t buf[7] = {
CMD_AM_TUNE_FREQ, 0x00,
(uint8_t)(freq >> 8), (uint8_t)(freq & 0xFF),
0x00, 0x00, /* ANTCAP=auto */
0x00,
};
if (!send_cmd(buf, 7)) return false;
}
if (!poll_stc(500)) return false;
return Si4732_refresh();
}
static uint16_t clamp_step_up(uint16_t f) {
uint32_t nf = (uint32_t)f + s_spacing;
if (nf > s_band_hi) nf = s_band_lo;
return (uint16_t)nf;
}
static uint16_t clamp_step_down(uint16_t f) {
if (f <= s_band_lo) return s_band_hi;
int32_t nf = (int32_t)f - s_spacing;
if (nf < s_band_lo) nf = s_band_hi;
return (uint16_t)nf;
}
static bool Si4732_freq_up(void) { return Si4732_tune(clamp_step_up(s_freq)); }
static bool Si4732_freq_down(void) { return Si4732_tune(clamp_step_down(s_freq)); }
static bool Si4732_seek(bool up) {
rds_clear();
uint8_t arg1 = 0x00;
if (up) arg1 |= 0x08; /* SEEKUP */
arg1 |= 0x04; /* WRAP at band limits */
if (s_mode == SI4732_MODE_FM) {
uint8_t buf[2] = { CMD_FM_SEEK_START, arg1 };
if (!send_cmd(buf, 2)) return false;
} else {
uint8_t buf[6] = { CMD_AM_SEEK_START, arg1, 0x00, 0x00, 0x00, 0x00 };
if (!send_cmd(buf, 6)) return false;
}
if (!poll_stc(8000)) return false; /* seek can be slow */
if (!Si4732_refresh()) return false;
/* Re-read tune status to inspect BLTF */
uint8_t cmd[2] = {
(s_mode == SI4732_MODE_FM) ? CMD_FM_TUNE_STATUS : CMD_AM_TUNE_STATUS,
0x01
};
uint8_t resp[8] = { 0 };
if (!send_cmd_read(cmd, 2, resp, 8)) return false;
return (resp[1] & TUNE_STATUS_BLTF) == 0;
}
/* -------- Volume / mute / RDS ------------------------------------------ */
static void Si4732_set_volume(uint8_t vol) {
if (vol > 63) vol = 63;
s_volume = vol;
set_property(PROP_RX_VOLUME, vol);
}
static uint8_t Si4732_volume(void) { return s_volume; }
static void Si4732_volume_up(void) {
Si4732_set_volume((s_volume < 63) ? (uint8_t)(s_volume + 1) : 63);
}
static void Si4732_volume_down(void) {
Si4732_set_volume((s_volume > 0) ? (uint8_t)(s_volume - 1) : 0);
}
static void Si4732_set_mute(bool on) {
set_property(PROP_RX_HARD_MUTE, on ? 0x0003 : 0x0000);
}
static bool Si4732_rds_poll(void) {
if (s_mode != SI4732_MODE_FM) return false;
/* Pop one group from the chip's FIFO. INTACK=1 clears RDSINT. */
uint8_t cmd[2] = { CMD_FM_RDS_STATUS, 0x01 };
uint8_t resp[13] = { 0 };
if (!send_cmd_read(cmd, 2, resp, 13)) return false;
rds_sync = (resp[2] & 0x01) != 0;
uint8_t in_fifo = resp[3];
if (in_fifo == 0) return false;
/* Bytes 4..11 = blocks A,B,C,D (MSB first), byte 12 = blk error flags */
uint16_t blkB = ((uint16_t)resp[6] << 8) | resp[7];
uint16_t blkC = ((uint16_t)resp[8] << 8) | resp[9];
uint16_t blkD = ((uint16_t)resp[10] << 8) | resp[11];
uint8_t group_type = (uint8_t)((blkB >> 12) & 0xF);
uint8_t version_b = (uint8_t)((blkB >> 11) & 0x1);
if (group_type == 0) {
uint8_t pos = (uint8_t)(blkB & 0x3);
char c0 = (char)(blkD >> 8);
char c1 = (char)(blkD & 0xFF);
rds_ps[pos * 2 + 0] = (c0 >= 0x20 && c0 < 0x7F) ? c0 : ' ';
rds_ps[pos * 2 + 1] = (c1 >= 0x20 && c1 < 0x7F) ? c1 : ' ';
} else if (group_type == 2 && version_b == 0) {
uint8_t seg = (uint8_t)(blkB & 0xF);
int8_t ab = (int8_t)((blkB >> 4) & 0x1);
if (rds_rt_ab != ab) {
for (uint8_t i = 0; i < 64; i++) rds_rt[i] = ' ';
rds_rt_ab = ab;
}
char c[4] = {
(char)(blkC >> 8), (char)(blkC & 0xFF),
(char)(blkD >> 8), (char)(blkD & 0xFF)
};
for (uint8_t i = 0; i < 4; i++) {
rds_rt[seg * 4 + i] = (c[i] >= 0x20 && c[i] < 0x7F) ? c[i] : ' ';
}
}
return true;
}
static const char *Si4732_rds_ps(void) { return rds_ps; }
static const char *Si4732_rds_rt(void) { return rds_rt; }
static bool Si4732_get_rev(uint8_t *pn, uint8_t *fwmaj, uint8_t *fwmin,
uint16_t *patch_id, uint8_t *cmpmaj, uint8_t *cmpmin,
uint8_t *chiprev) {
uint8_t cmd = CMD_GET_REV;
uint8_t resp[9] = { 0 };
if (!send_cmd_read(&cmd, 1, resp, 9)) return false;
if (pn) *pn = resp[1];
if (fwmaj) *fwmaj = resp[2];
if (fwmin) *fwmin = resp[3];
if (patch_id) *patch_id = ((uint16_t)resp[4] << 8) | resp[5];
if (cmpmaj) *cmpmaj = resp[6];
if (cmpmin) *cmpmin = resp[7];
if (chiprev) *chiprev = resp[8];
return true;
}
static uint16_t Si4732_freq(void) { return s_freq; }
static uint8_t Si4732_rssi(void) { return s_rssi; }
static uint8_t Si4732_snr(void) { return s_snr; }
static bool Si4732_stereo(void) { return s_stereo; }
/* ============================================================================
* Application — UART console
* ========================================================================== */
static void show_help(void) {
UART1_send_string("\r\n=== Si4732 radio ===\r\n");
UART1_send_string(" u/U freq up (1 step)\r\n");
UART1_send_string(" d/D freq down (1 step)\r\n");
UART1_send_string(" S seek up\r\n");
UART1_send_string(" s seek down\r\n");
UART1_send_string(" + volume up\r\n");
UART1_send_string(" - volume down\r\n");
UART1_send_string(" m toggle mute\r\n");
UART1_send_string(" F FM band\r\n");
UART1_send_string(" A AM/MW band\r\n");
UART1_send_string(" W SW 31m band\r\n");
UART1_send_string(" 0 status\r\n");
UART1_send_string(" r RDS (PS + RT, FM only)\r\n");
UART1_send_string(" i chip revision\r\n");
UART1_send_string(" ? help\r\n");
}
static void show_status(void) {
char s[96];
Si4732_refresh();
uint16_t f = Si4732_freq();
if (Si4732_mode() == SI4732_MODE_FM) {
snprintf(s, sizeof(s),
"[Si4732] FM %u.%02u MHz RSSI=%u SNR=%u ST=%u VOL=%u\r\n",
f / 100, f % 100,
Si4732_rssi(), Si4732_snr(),
Si4732_stereo() ? 1 : 0,
Si4732_volume());
} else {
snprintf(s, sizeof(s),
"[Si4732] AM %u kHz RSSI=%u SNR=%u VOL=%u\r\n",
f, Si4732_rssi(), Si4732_snr(), Si4732_volume());
}
UART1_send_string(s);
}
static void show_revision(void) {
char s[96];
uint8_t pn, fwmaj, fwmin, cmpmaj, cmpmin, chiprev;
uint16_t patch;
if (!Si4732_get_rev(&pn, &fwmaj, &fwmin, &patch, &cmpmaj, &cmpmin, &chiprev)) {
UART1_send_string("[Si4732] GET_REV failed\r\n");
return;
}
snprintf(s, sizeof(s),
"[Si4732] PN=0x%02X FW=%c.%c Patch=0x%04X CMP=%c.%c CHIPREV=%c\r\n",
pn, fwmaj, fwmin, patch, cmpmaj, cmpmin, chiprev);
UART1_send_string(s);
}
static void show_rds(void) {
const uint16_t IDLE_TIMEOUT_MS = 5000;
const uint8_t WINDOW = 32;
const uint8_t FRAME_MS = 200;
uint16_t idle_ms = 0;
uint8_t offset = 0;
char line[80];
char window[33];
if (Si4732_mode() != SI4732_MODE_FM) {
UART1_send_string("[RDS] only available in FM mode\r\n");
return;
}
UART1_send_string("\r\n[RDS] marquee (any key stops)\r\n");
while (idle_ms < IDLE_TIMEOUT_MS) {
for (uint8_t t = 0; t < FRAME_MS / 10; t++) {
if (UART1_rx_available()) {
UART1_read();
UART1_send_string("\r\n[RDS] stopped\r\n");
return;
}
if (Si4732_rds_poll()) idle_ms = 0;
_delay_ms(10);
}
idle_ms += FRAME_MS;
const char *rt = Si4732_rds_rt();
for (uint8_t i = 0; i < WINDOW; i++) {
window[i] = rt[(offset + i) % 64];
}
window[WINDOW] = '\0';
snprintf(line, sizeof(line), "\r %-8s | %s ", Si4732_rds_ps(), window);
UART1_send_string(line);
offset = (uint8_t)((offset + 1) % 64);
}
UART1_send_string("\r\n[RDS] stopped (idle)\r\n");
}
/* ============================================================================
* main
* ========================================================================== */
int main(void) {
bool muted = false;
CCP = CCP_IOREG_gc;
CLKCTRL.OSCHFCTRLA = CLKCTRL_FRQSEL_24M_gc;
UART1_init();
UART1_send_string("[Si4732] boot\r\n");
if (!Si4732_init(SI4732_MODE_FM)) {
UART1_send_string("[Si4732] init FAILED\r\n");
while (1);
}
show_revision();
if (!Si4732_tune(8830)) { /* 88.3 MHz */
UART1_send_string("[Si4732] tune FAILED\r\n");
}
show_status();
show_help();
while (1) {
if (Si4732_mode() == SI4732_MODE_FM) Si4732_rds_poll();
if (!UART1_rx_available()) continue;
char c = UART1_read();
switch (c) {
case 'u': case 'U': Si4732_freq_up(); show_status(); break;
case 'd': case 'D': Si4732_freq_down(); show_status(); break;
case 'S': Si4732_seek(true); show_status(); break;
case 's': Si4732_seek(false); show_status(); break;
case '+': Si4732_volume_up(); show_status(); break;
case '-': Si4732_volume_down();show_status(); break;
case 'm': muted = !muted; Si4732_set_mute(muted);
UART1_send_string(muted ? "[mute on]\r\n" : "[mute off]\r\n");
break;
case 'F': Si4732_set_mode(SI4732_MODE_FM);
Si4732_tune(8830); show_status(); break;
case 'A': Si4732_set_mode(SI4732_MODE_AM);
Si4732_set_band(520, 1710, 10);
Si4732_tune(810); show_status(); break;
case 'W': Si4732_set_mode(SI4732_MODE_AM);
Si4732_set_band(9400, 9900, 5);
Si4732_tune(9650); show_status(); break;
case '0': show_status(); break;
case 'r': show_rds(); break;
case 'i': show_revision(); break;
case '?': show_help(); break;
case '\r': case '\n': break;
default: UART1_send_string("? (try '?')\r\n"); break;
}
}
}
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