From 63366dddd6a6152187aa76971262fc5def1467a1 Mon Sep 17 00:00:00 2001
From: Andreas Watterott <1488433+awatterott@users.noreply.github.com>
Date: Sun, 28 Mar 2021 16:56:27 +0200
Subject: [PATCH 1/2] check I2C baudrate prescaler range
---
cores/arduino/SERCOM.cpp | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/cores/arduino/SERCOM.cpp b/cores/arduino/SERCOM.cpp
index b9fbf05b9..bb7829188 100644
--- a/cores/arduino/SERCOM.cpp
+++ b/cores/arduino/SERCOM.cpp
@@ -458,7 +458,12 @@ void SERCOM::initMasterWIRE( uint32_t baudrate )
// sercom->I2CM.INTENSET.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR ;
// Synchronous arithmetic baudrate
- sercom->I2CM.BAUD.bit.BAUD = SystemCoreClock / ( 2 * baudrate) - 5 - (((SystemCoreClock / 1000000) * WIRE_RISE_TIME_NANOSECONDS) / (2 * 1000));
+ baudrate = SystemCoreClock / ( 2 * baudrate) - 5 - (((SystemCoreClock / 1000000) * WIRE_RISE_TIME_NANOSECONDS) / (2 * 1000));
+ if(baudrate > 255) // I2C baud rate is 8bit
+ {
+ baudrate = 255;
+ }
+ sercom->I2CM.BAUD.bit.BAUD = baudrate;
}
void SERCOM::prepareNackBitWIRE( void )
From 64b6fca042eb2d72834af3c8e37ea9bf353ccfc3 Mon Sep 17 00:00:00 2001
From: Andreas Watterott <1488433+awatterott@users.noreply.github.com>
Date: Sun, 28 Mar 2021 17:01:33 +0200
Subject: [PATCH 2/2] I2C rx+tx timeout
---
cores/arduino/SERCOM.cpp | 49 ++++++++++++++++++++++++++--------------
1 file changed, 32 insertions(+), 17 deletions(-)
diff --git a/cores/arduino/SERCOM.cpp b/cores/arduino/SERCOM.cpp
index bb7829188..77f497017 100644
--- a/cores/arduino/SERCOM.cpp
+++ b/cores/arduino/SERCOM.cpp
@@ -524,28 +524,41 @@ bool SERCOM::startTransmissionWIRE(uint8_t address, SercomWireReadWriteFlag flag
// Address Transmitted
if ( flag == WIRE_WRITE_FLAG ) // Write mode
{
- while( !sercom->I2CM.INTFLAG.bit.MB )
+ // The loop takes about 100us @ 100kHz baudrate.
+ // Timeout: 20ms = 10000*2us
+ for(uint16_t tmr = 10000; tmr; tmr--)
{
+ if(sercom->I2CM.INTFLAG.bit.MB) // byte is transmitted
+ {
+ // Check for loss of arbitration (multiple masters starting communication at the same time)
+ if(!isBusOwnerWIRE())
+ {
+ // Restart communication
+ sercom->I2CM.ADDR.bit.ADDR = address;
+ }
+ else
+ {
+ break;
+ }
+ }
// Wait transmission complete
- }
- // Check for loss of arbitration (multiple masters starting communication at the same time)
- if(!isBusOwnerWIRE())
- {
- // Restart communication
- startTransmissionWIRE(address >> 1, flag);
+ delayMicroseconds(2); // wait 2us
}
}
else // Read mode
{
- while( !sercom->I2CM.INTFLAG.bit.SB )
+ // The loop takes about 200us @ 100kHz baudrate.
+ // Timeout: 20ms = 10000*2us
+ for(uint16_t tmr = 10000; tmr && !sercom->I2CM.INTFLAG.bit.SB; tmr--)
{
- // If the slave NACKS the address, the MB bit will be set.
- // In that case, send a stop condition and return false.
- if (sercom->I2CM.INTFLAG.bit.MB) {
- sercom->I2CM.CTRLB.bit.CMD = 3; // Stop condition
- return false;
- }
+ // If the slave NACKS the address, the MB bit will be set.
+ // In that case, send a stop condition and return false.
+ if (sercom->I2CM.INTFLAG.bit.MB) {
+ sercom->I2CM.CTRLB.bit.CMD = 3; // Stop condition
+ return false;
+ }
// Wait transmission complete
+ delayMicroseconds(2); // wait 2us
}
// Clean the 'Slave on Bus' flag, for further usage.
@@ -569,14 +582,16 @@ bool SERCOM::sendDataMasterWIRE(uint8_t data)
//Send data
sercom->I2CM.DATA.bit.DATA = data;
- //Wait transmission successful
- while(!sercom->I2CM.INTFLAG.bit.MB) {
-
+ // Wait transmission successful
+ // The loop takes about 100us @ 100kHz baudrate.
+ // Timeout: 20ms = 10000*2us
+ for(uint16_t tmr = 10000; tmr && !sercom->I2CM.INTFLAG.bit.MB; tmr--) {
// If a bus error occurs, the MB bit may never be set.
// Check the bus error bit and bail if it's set.
if (sercom->I2CM.STATUS.bit.BUSERR) {
return false;
}
+ delayMicroseconds(2); // wait 2us
}
//Problems on line? nack received?