mattytrentini / micropython-mcp7940 Goto Github PK

The MCP7940 has 64 bytes of onboard storage that is retained when the RTC is powered by a battery.

Seems like this would be best implemented with a slice operator:

mcp.data[0:10] = range(10) # Set first ten bytes to 1..10
fourth = mcp.data[4] # Read fourth byte

The MCP supports calibration of the oscillator. We need to expose the fields to allow the calibration to occur.

Although there's an is_leap_year function - and it's been tested - it's not currently used.

It should be used when setting the time on the MCP so the RTC knows how to increment time as it rolls through February.

Hi, I created a fork of your repo (by using the tinyPICO fork of it that is).
Beside the fact that the file mcp7940.py has an is_leap_year function, I see that this function is only mentioned in the commentary but nowhere called from inside the class. Since I decided to use the is_leap_year function, which I needed for an added yearday function, I discovered that the function defintion of the is_leap_year function has no self defined as first parameter, like I did:
def is_leap_year(self, year):

Without self the function could be called with e.g.: MCP7940.is_leap_year(current_year)

I see that you did this also with the functions bcd_to_int(bcd): and def int_to_bcd(i): and call these from within the same class with t = [(MCP7940.int_to_bcd(reg) & filt) for reg, filt in zip(time_reg, reg_filter)] in function alarm1.

and with t = [MCP7940.bcd_to_int(reg & filt) for reg, filt in zip(time_reg, reg_filter)] in the function _get_time.

Can I ask you why you have chosen to do the function calls as: MCP7940.int_to_bcd and MCP7940.bcd_to_int and not through self.int_to_bcd or self.bcd_to_int ?

There are some generally useful functions that should not be contained in MCP7940. The following functions are candidates:

• is_leap_year
• bcd_to_int/int_to_bcd
• _set_bit/_read_bit

The corresponding tests should also be moved.

Since 2020 is a leap year, the leap year bit is being set in the month register and was throwing off the month returned by x20 when getting mcp7940 time. I changed the mask for that register from x3F to x1F:

def _get_time(self, start_reg = 0x00):
    num_registers = 7 if start_reg == 0x00 else 6
    time_reg = self._i2c.readfrom_mem(MCP7940.ADDRESS, start_reg, num_registers)  # Reading too much here for alarms
    # reg_filter = (0x7F, 0x7F, 0x3F, 0x07, 0x3F, 0x3F, 0xFF)[:num_registers]
    # changed month mask from x3F to x1F to mask off leap year bit
    reg_filter = (0x7F, 0x7F, 0x3F, 0x07, 0x3F, 0x1F, 0xFF)[:num_registers]

The MCP supports two alarms; need to add to the API.

Maybe:

mcp.alarm1.time = alarmtime # Set to None to stop alarm?
mcp.alarm.mask = # An OR'd enum here?
mcp.alarm1.time # Read alarm
mcp.alarm2.time = alarmtime2 

The MCP has various output configurations that can control the MFP pin. The alarm output is the most commonly used; MFP will be modified when the alarms are raised.

However there is support to also generate a square wave or a GPIO signal if the alarm output is not configured. These features should be exposed.

Hi,

How install it on micropython ?

Sincerely
Eric

utime.localtime includes yearday in it's representation of time.

For compatibility it would be nice to return the right yearday number. Currently 0 is returned.