Cracked it - can connect the DS3231 to any 2 digital pins of my Nano and read the date, time, and temperature by making use of the B4A core library only. All control of the SDA (data) and SCL (clock) lines are hard coded. So, don't have to connect it to the traditional I2C pins and don't have to use a DS3231 or the Wire library.
By no means perfect and no error checking incorporated - just wanted to see if I could "hard code" a read from the DS3231 by making use of any 2 digital configured pins. In the attached sample I am using pins 10 (data) and 11 (clock) of my Nano to communicate with the DS3231 RTC module (I2C is traditionally pins A4 and A5 on the Nano)
It was a bit tricky to figure it out - especially reading from the DS3231 as it involves a start, a write, then a repeated start, a write, and then a read process.
Along with this project (combining them) one should be able to set time and date of the DS3231 and then also read time, date, and temperature from the DS3231 using any 2 digital pins.
By no means perfect and no error checking incorporated - just wanted to see if I could "hard code" a read from the DS3231 by making use of any 2 digital configured pins. In the attached sample I am using pins 10 (data) and 11 (clock) of my Nano to communicate with the DS3231 RTC module (I2C is traditionally pins A4 and A5 on the Nano)
It was a bit tricky to figure it out - especially reading from the DS3231 as it involves a start, a write, then a repeated start, a write, and then a read process.
Along with this project (combining them) one should be able to set time and date of the DS3231 and then also read time, date, and temperature from the DS3231 using any 2 digital pins.
B4X:
#Region Project Attributes
#AutoFlushLogs: True
#CheckArrayBounds: True
#StackBufferSize: 300
#End Region
Sub Process_Globals
'These global variables will be declared once when the application starts.
'Public variables can be accessed from all modules.
Public Serial1 As Serial
Dim pclk, pdat As Pin
'comment out the below two lines and un-comment the following two line to use for eg pins 10 (data) and 11 (clock)
' Dim pdatNo As Byte = pdat.A4 'pin A4 on the Nano is the default pin for the I2C data line
' Dim pclkNo As Byte = pclk.A5 'pin A5 on the Nano is the default pin for the I2C clock line
Dim pdatNo As Byte = 10 'with the code below any digital pin can be used as the data pin - the I2C comms is hard coded and not tied to a specific pin
Dim pclkNo As Byte = 11 'with the code below any digital pin can be used as the clock pin - the I2C comms is hard coded and not tied to a specific pin
Dim weekday()As String = Array As String("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday")
Dim t As Timer
End Sub
Private Sub AppStart
Serial1.Initialize(115200)
Log("AppStart")
t.Initialize("t_tick", 1000)
pclk.Initialize(pclkNo, pclk.MODE_OUTPUT)
pdat.Initialize(pdatNo, pdat.MODE_OUTPUT)
pclk.DigitalWrite(True) 'put both lines in idle mode (i.e both lines high)
pdat.DigitalWrite(True)
Delay(100) 'give the lines some time to settle to the new states
Delay(100)
t.Enabled = True
End Sub
Sub t_tick
Dim myminutes As Byte = 0
myminutes = GetMinutes 'get the minutes - 0.....59
Dim myhours As Byte = 0
myhours = GetHours 'get the hours - 0.....23
Dim myseconds As Byte = 0
myseconds = GetSeconds 'get the seconds - 0.....59
Dim myyear As Byte = 0 'get the year - 0.....99
myyear = GetYear
Dim mymonth As Byte = 0 'get the month - 1....12
mymonth = GetMonth
Dim myday As Byte = 0 'get the day of the month - 1.....31
myday = GetDay
Dim mydow As Byte = 0 'get the day of the week - 1....7 (see array weekday() above)
mydow = GetDayOfWeek
Dim mytemperatureInt As Byte = 0 'get the integer part of the temperature - degrees C
mytemperatureInt = GetTemperatureInt
Dim mytemperatureFrac As Byte = 0 'get the fraction part of the temperature - degrees C (resulotion is 0.25 degrees C)
mytemperatureFrac = GetTemperatureFrac
Dim finaltemperature As Float = mytemperatureInt + (mytemperatureFrac/100)
Log("Time = ", NumberFormat(myhours, 2,0), ":", _
NumberFormat(myminutes, 2,0), ":", _
NumberFormat(myseconds, 2,0), " ", _
NumberFormat(myyear, 2,0), "/", _
NumberFormat(mymonth, 2,0), "/", _
NumberFormat(myday, 2,0), " ", weekday(mydow-1), " Temperature = ", _
NumberFormat(finaltemperature, 2,2), " degrees C")
End Sub
Sub GetMinutes() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x01 'address of the register that holds the MINUTES data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the MINUTES (0....59)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetHours() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x02 'address of the register that holds the HOURS data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the HOURS (0....23)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetSeconds() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x00 'address of the register that holds the SECONDS data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the SECONDS (0....59)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetYear() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x06 'address of the register that holds the YEAR data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the YEAR (0....99)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetMonth() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x05 'address of the register that holds the MONTH data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the MONTH (1....12)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetDay() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x04 'address of the register that holds the DAY OF MONTH data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the DAY OF MONTH (1....7)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetDayOfWeek() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x03 'address of the register that holds the DAY OF WEEK data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the DAY OF WEEK (0....59)
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetTemperatureInt() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x11 'address of the register that holds the INTEGER OF TEMPERATURE data in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the INTEGER OF TEMPERATURE
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
Dim min10, min1 As Byte = 0
min10 = Bit.And(myvalue, 0xf0)
min10 = Bit.ShiftRight(min10, 4)
min10 = min10 * 10
min1 = Bit.And(myvalue, 0x0f)
myvalue = min10 + min1
Return myvalue
End Sub
Sub GetTemperatureFrac() As Byte
setStartCondition 'create a START condition for the DS3231 - the data line needs to go from high to low while the clock is high
clockInDS3231Address(0xD0) 'send the DS3231 I2C address out on the I2C bus
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after address has been sent on the bus
Dim register As Byte = 0x12 'address of the register that holds the FRACTION of the TEMPERATURE in the DS3231
selectRegister(register) 'tell the DS3231 we want to work with the register that holds the FRACTION OF THE TEMPERATURE
checkAckFromDS3231 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStartCondition 'we need to set a new start condition in order to read the register that we have written to above
clockInDS3231Address(0xD1)
checkAckFromDS3231
Dim myvalue As Byte = getValue 'check if the DS3231 is sending back and ACK after 8 bits have been sent to it
setStopCondition 'generate STOP condition for the DS3231
myvalue = Bit.ShiftRight(myvalue,6)
If myvalue = 0 Then
myvalue = 0
else if myvalue = 1 Then
myvalue = 25
else if myvalue = 2 Then
myvalue = 50
else if myvalue = 3 Then
myvalue = 75
End If
Return myvalue
End Sub
Sub getValue() As Byte
Dim myvalue As Byte = 0
pdat.Initialize(pdatNo, pdat.MODE_INPUT) 'check for the ACK coming from the DS3231 - the line should be pulled low by the DS3231
DelayMicroseconds(2)
For i = 0 To 7
pclk.DigitalWrite(True)
DelayMicroseconds(2)
Dim pinstate As Boolean = pdat.DigitalRead
If pinstate = True Then
myvalue = Bit.Or(myvalue, 1)
Else
myvalue = Bit.Or(myvalue, 0)
End If
If i < 7 Then
myvalue = Bit.ShiftLeft(myvalue,1)
End If
' Log("data = ", pdat.DigitalRead)
pclk.DigitalWrite(False)
DelayMicroseconds(2)
Next
' Log("myvalue = ", myvalue)
pdat.Initialize(pdatNo, pdat.MODE_OUTPUT) 'We need to send a NACK (i.e not acknowledge)
pdat.DigitalWrite(True) 'take the data line high
pclk.DigitalWrite(True) 'take the clock high
DelayMicroseconds(2)
pclk.DigitalWrite(False) 'take the clock low
Return myvalue
End Sub
Sub selectRegister(register As Byte)
For i = 0 To 7
If Bit.And(register, 128) = 128 Then
pdat.DigitalWrite(True)
Else
pdat.DigitalWrite(False)
End If
DelayMicroseconds(2)
pclk.DigitalWrite(True)
DelayMicroseconds(2)
pclk.DigitalWrite(False)
DelayMicroseconds(2)
register = Bit.ShiftLeft(register, 1)
Next
End Sub
Sub setStopCondition
pdat.DigitalWrite(False) 'generate a stop condition - the data line must go from low to high while the clock is high
DelayMicroseconds(2)
pclk.DigitalWrite(True)
DelayMicroseconds(2)
pdat.DigitalWrite(True)
DelayMicroseconds(2)
End Sub
Sub setStartCondition
pdat.DigitalWrite(True) 'set a start condition i.e the data line must go from high to low while the clock is high
DelayMicroseconds(2)
pclk.DigitalWrite(True)
DelayMicroseconds(2)
pdat.DigitalWrite(False)
DelayMicroseconds(2)
pclk.DigitalWrite(False)
DelayMicroseconds(2)
End Sub
Sub clockInDS3231Address(address As Byte)
' Dim address As Byte = 0xD0 'address (7 bits) plus 8th bit added as LSB to indicate to the DS3231 that we want to write to it (address is 0x68 left shift 1 = 0xD0 to incliude the WRITE bit)
For i = 0 To 7
If Bit.And(address, 128) = 128 Then 'is the bit a 1?
pdat.DigitalWrite(True)
Else
pdat.DigitalWrite(False)
End If
DelayMicroseconds(2)
pclk.DigitalWrite(True)
DelayMicroseconds(2)
pclk.DigitalWrite(False)
DelayMicroseconds(2)
address = Bit.ShiftLeft(address, 1) 'shift the address byte 1 bit to the left for the next Bit.And operation
Next
End Sub
Sub checkAckFromDS3231
pdat.Initialize(pdatNo, pdat.MODE_INPUT) 'check for the ACK coming from the DS3231 - the line should be pulled low by the DS3231
DelayMicroseconds(2)
pclk.DigitalWrite(True) 'we need to generate a 9th clock for every byte to read the ACK from the DS3231 - take the clock high
DelayMicroseconds(2)
' Log("pdat mode 1 = ", pdat.DigitalRead) 'check id the DS3231 has pulled the data line low
pclk.DigitalWrite(False) 'take the clock low
pdat.Initialize(pdatNo, pdat.MODE_OUTPUT) 'put the data pin back into output mode
pdat.DigitalWrite(True) 'take the data line back to high i.e normal idle mode
End Sub
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