From 114dfd624a977449de9be7b32cf79004d2613f79 Mon Sep 17 00:00:00 2001
From: Erik Strand <erik.strand@cba.mit.edu>
Date: Sun, 12 May 2019 16:08:47 -0400
Subject: [PATCH] Read an SD card, if somewhat unreliably
Bit banging is not the way to go.
---
sd_tests/neil/read_sd.c | 123 +++++++++++++++++++++++++---------------
1 file changed, 76 insertions(+), 47 deletions(-)
diff --git a/sd_tests/neil/read_sd.c b/sd_tests/neil/read_sd.c
index 65e67f6..936a263 100644
--- a/sd_tests/neil/read_sd.c
+++ b/sd_tests/neil/read_sd.c
@@ -221,7 +221,7 @@ unsigned char SPI_write(uint8_t chr) {
// SD_command
// write an SD command and return the response
//
-void SD_command(uint8_t command,uint32_t argument,uint8_t CRC,uint8_t *result) {
+void SD_command(uint8_t command, uint32_t argument, uint8_t CRC, uint8_t *result) {
clear(CS_port,CS_pin);
SPI_write(command);
SPI_write((argument >> 24) & 0xFF);
@@ -300,49 +300,22 @@ void SD_read(uint32_t sector,uint16_t offset,uint8_t *buffer,uint16_t size) {
set(CS_port,CS_pin);
}
-//
-// main
-//
-int main(void) {
- //
- // main
- //
+void sd_loop() {
+ static uint8_t count, sectors_per_cluster, FATs, attribute, result[8], buffer[50];
+ static uint16_t bytes_per_sector, reserved_sectors, offset, file_cluster_low, file_cluster_hi,
+ buffer_length, sector_count;
+ static uint32_t partition, FAT_sectors, fat_sector, root_cluster, root_sector, file_length,
+ file_cluster, file_sector, chars_read;
- // Debug loop to verify we can detect when the card is inserted
- // Configure DETECT_pin as an input and led_pin as an output
- DETECT_direction &= ~DETECT_pin;
- led_direction |= led_pin;
- while (1) {
- if (PINA & DETECT_pin) {
- led_port &= ~led_pin;
- } else {
- led_port |= led_pin;
- }
+ // Wait for card to be inserted
+ while (PINA & DETECT_pin) {
+ led_port |= led_pin;
+ _delay_ms(200);
+ led_port &= ~led_pin;
+ _delay_ms(200);
}
+ led_port |= led_pin;
- static uint8_t count,sectors_per_cluster,FATs,attribute,result[8],buffer[50];
- static uint16_t bytes_per_sector,reserved_sectors,offset,
- file_cluster_low,file_cluster_hi,buffer_length,sector_count;
- static uint32_t partition,FAT_sectors,fat_sector,root_cluster,
- root_sector,file_length,file_cluster,file_sector,chars_read;
- //
- // set clock divider to /1
- //
- CLKPR = (1 << CLKPCE);
- CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
- //
- // initialize output pins
- //
- set(serial_port,serial_pin_out);
- output(serial_direction,serial_pin_out);
- set(CS_port,CS_pin);
- output(CS_direction,CS_pin);
- clear(MOSI_port,MOSI_pin);
- output(MOSI_direction,MOSI_pin);
- set(SCK_port,SCK_pin);
- output(SCK_direction,SCK_pin);
- set(MISO_port,MISO_pin); //turn on pull-up
- input(MISO_direction,MISO_pin);
//
// put card in SPI mode
//
@@ -354,20 +327,23 @@ int main(void) {
clear(SCK_port,SCK_pin);
SPI_delay();
}
+
//
// CMD0: reset and enter idle state
// should return 0x01
//
put_flash_string(PSTR("\r\nreset: 0x"));
- SD_command(0x40,0,0x95,result);
+ SD_command(0x40, 0, 0x95, result);
put_hex_string(result,8);
+
//
// CMD8: send interface condition, set SDHC
// should return 0x01000001AA
//
put_flash_string(PSTR("\r\nset interface: 0x"));
- SD_command(0x48,0x000001AA,0x87,result);
+ SD_command(0x48, 0x000001AA, 0x87, result);
put_hex_string(result,8);
+
//
// initialization loop
//
@@ -378,21 +354,31 @@ int main(void) {
// should return 0x01
//
put_flash_string(PSTR("\r\n application command: "));
- SD_command(0x77,0,0,result);
- put_hex_string(result,8);
+ SD_command(0x77, 0, 0, result);
+ put_hex_string(result, 8);
+
//
// ACMD41: initialize the card
// should return 0x00 when ready
//
put_flash_string(PSTR("\r\n initialize card: 0x"));
- SD_command(0x69,0x40000000,0,result);
+ SD_command(0x69, 0x40000000, 0, result);
put_hex_string(result,8);
+
//
// check if done
//
- if (result[1] == 0)
+ if (result[1] == 0) {
+ put_string("\ncard initialized");
break;
}
+
+ if (PINA & DETECT_pin) {
+ put_string("\ncard removed");
+ return;
+ }
+ }
+
//
// read the first partition table
//
@@ -403,6 +389,7 @@ int main(void) {
put_flash_string(PSTR("\r\n first sector: 0x"));
put_hex_string(buffer+8,4);
memcpy(&partition,buffer+8,4);
+
//
// read the first partition block
//
@@ -442,6 +429,7 @@ int main(void) {
put_hex_char((root_cluster >> 16) & 0xFF);
put_hex_char((root_cluster >> 8) & 0xFF);
put_hex_char(root_cluster & 0xFF);
+
//
// read the root directory
//
@@ -498,6 +486,7 @@ int main(void) {
}
offset += 32;
}
+
//
// read the file
//
@@ -520,6 +509,7 @@ int main(void) {
put_char_string(buffer,buffer_length);
chars_read += buffer_length;
offset += buffer_length;
+
//
// check sector length
//
@@ -549,9 +539,48 @@ int main(void) {
offset = 0;
}
}
+
//
// sector length not reached, continue
//
}
put_flash_string(PSTR("\r\n\r\nend of file\r\n"));
+ led_port &= ~led_pin;
+}
+
+//
+// main
+//
+int main(void) {
+ //
+ // main
+ //
+
+ //
+ // set clock divider to /1
+ //
+ CLKPR = (1 << CLKPCE);
+ CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
+
+ // Configure DETECT_pin as an input and led_pin as an output
+ DETECT_direction &= ~DETECT_pin;
+ led_direction |= led_pin;
+
+ //
+ // initialize output pins
+ //
+ set(serial_port,serial_pin_out);
+ output(serial_direction,serial_pin_out);
+ set(CS_port,CS_pin);
+ output(CS_direction,CS_pin);
+ clear(MOSI_port,MOSI_pin);
+ output(MOSI_direction,MOSI_pin);
+ set(SCK_port,SCK_pin);
+ output(SCK_direction,SCK_pin);
+ set(MISO_port,MISO_pin); //turn on pull-up
+ input(MISO_direction,MISO_pin);
+
+ while (1) {
+ sd_loop();
+ }
}
--
GitLab