1 files changed, 74 insertions, 29 deletions

diff --git a/fw/eeprom.c b/fw/eeprom.c
index 567cdc1..e832fa0 100644
--- a/fw/eeprom.c
+++ b/fw/eeprom.c
@@ -12,6 +12,12 @@
 // 16-byte page ('C' variant)
 #define PAGE_SIZE 16u
 
+// Write cycle time = 5ms
+// 5ms / (4*Tosc) = 60000
+#define WRITE_DELAY 60000u
+
+#define BAILOUT 10u
+
 // Commands
 enum {
 	CMD_READ = 0x03,
@@ -30,42 +36,52 @@ enum {
 	STATUS_BP1 = 0x8, // block protection 1
 };
 
-// Timing
-enum {
-	TIME_WRITE_CYCLE_MS = 5,
-};
+static U8
+readStatus(void) {
+	U8 status;
 
-void
-eepromInit(void) {
-	EEPROM_CS_TRIS = OUT;
+	EEPROM_CS = 0;
+	(void)spiTx(CMD_READ_STATUS);
+	status = spiTx(0x00);
 	EEPROM_CS = 1;
-
-	eepromWriteDisable();
+	return status;
 }
 
-void
-eepromWriteEnable(void) {
+static Status
+writeEnable(void) {
 	EEPROM_CS = 0;
 	(void)spiTx(CMD_WRITE_ENABLE);
 	EEPROM_CS = 1;
+
+	return (readStatus() & STATUS_WEL) ? OK : FAIL;
 }
 
-void
-eepromWriteDisable(void) {
+static void
+writeDisable(void) {
 	EEPROM_CS = 0;
 	(void)spiTx(CMD_WRITE_DISABLE);
 	EEPROM_CS = 1;
 }
 
-static bool
-isWriteInProgress(void) {
-	U8 status;
-
-	EEPROM_CS = 0;
-	(void)spiTx(CMD_READ_STATUS);
-	status = spiTx(0x00);
+void
+eepromInit(void) {
+	EEPROM_CS_TRIS = OUT;
 	EEPROM_CS = 1;
-	return status & STATUS_WIP;
+
+	writeDisable();
+}
+
+// Wait for pending write to finish
+static Status
+waitForWrite(void) {
+	U8 status, k;
+
+	status = readStatus();
+	for (k = 0u; (status & STATUS_WIP) && (k < BAILOUT); k++) {
+		_delay(WRITE_DELAY);
+		status = readStatus();
+	}
+	return (k < BAILOUT) ? OK : FAIL;
 }
 
 static void
@@ -79,12 +95,24 @@ isPageStart(U16 addr) {
 	return (addr.lo % PAGE_SIZE) == 0;
 }
 
-void
+Status
 eepromWrite(U16 addr, U8 *data, U8 size) {
-	while (isWriteInProgress()) {} // wait for previous write to finish
+	Status status;
 
-	EEPROM_CS = 0; // pull chip-select low
+	// Wait for pending write to finish
+	status = waitForWrite();
+	if (status != OK) {
+		return FAIL; // timed out
+	}
+
+	// Set write-enable
+	status = writeEnable();
+	if (status != OK) {
+		return FAIL;
+	}
 
+	// Write
+	EEPROM_CS = 0;
 	(void)spiTx(CMD_WRITE);
 	spiTxAddr(addr);
 	while (size--) {
@@ -96,7 +124,14 @@ eepromWrite(U16 addr, U8 *data, U8 size) {
 		if (isPageStart(addr) && size) {
 			// Write current page to memory
 			EEPROM_CS = 1;
-			while (isWriteInProgress()) {}
+			status = waitForWrite();
+			if (status != OK) {
+				return FAIL; // timed out
+			}
+			status = writeEnable();
+			if (status != OK) {
+				return FAIL;
+			}
 			EEPROM_CS = 0;
 
 			// Start next page
@@ -104,20 +139,30 @@ eepromWrite(U16 addr, U8 *data, U8 size) {
 			spiTxAddr(addr);
 		}
 	}
+	EEPROM_CS = 1;
 
-	EEPROM_CS = 1; // release chip-select
+	return OK;
 }
 
-void
+Status
 eepromRead(U16 addr, U8 *data, U8 size) {
-	EEPROM_CS = 0; // pull chip-select low
+	Status status;
+
+	// Wait for pending write to finish
+	status = waitForWrite();
+	if (status != OK) {
+		return FAIL; // timed out
+	}
 
+	// Read
+	EEPROM_CS = 0;
 	(void)spiTx(CMD_READ);
 	spiTxAddr(addr);
 	while (size--) {
 		*data = spiTx(0x00);
 		data++;
 	}
+	EEPROM_CS = 1;
 
-	EEPROM_CS = 1; // release chip-select
+	return OK;
 }