Requesting Guidance on Proper Way to Call rd_block(p_block, count, ackbit) in jm_i2c.spin2

CJMJ

@JonnyMac What's the proper way to use this call with an array of bytes? Currently, I'm trying the following:

obj
i2c : "jm_i2c"
var
byte data[30]

pub go()
...
i2c.rd_block(@data,7,i2c.NAK)
...

I just want to verify I'm call the method correctly.

JonnyMac

Your syntax is correct. Are you having problems? I do my best to test code very carefully, but I am in fact human.

CJMJ

I doubt it's your code. I'm sure I'm doing something wrong. I'm trying to read multiple registers at a time from a RV-3028-C7 RTC. I can write to it fine and read each register independently but I've yet to have a successful multiple register read. I may need to set a mode or something. I'm getting all $FF's instead of the expected values 00,01,02,03,etc. As soon as I finish helping my brother from Lake Charles unload his truck, I'll get back to the fun stuff. If I can't get it by tonight I'll post some code. Thanks.

JonnyMac

I just finished coding the Click RTC 10 object a few days ago. This method lets you do that -- should be similar for your RTC.

pub generic_read(r, p_buf, len)

'' Read block of registers from RTC to p_buf
'' -- r is first register
'' -- p_buf is pointer to destination bytes
'' -- len is number of registers to read

  i2c.start()
  i2c.write(DS3231M_WR)
  i2c.write(r)
  i2c.start()
  i2c.write(DS3231M_RD)
  i2c.rd_block(p_buf, len, i2c.NAK)
  i2c.stop()

Remember... to do an I2C read you have to restart and send the slave address with bit 0 set to 1. I have these constants in my object.

  DS3231M_WR = %1101_000_0                                      ' i2c slave id
  DS3231M_RD = %1101_000_1

JonnyMac

A few minutes later...
You should be able to write a routine like this for your RTC (Warning: not tested, not polished -- change magic #s to constants)

pub get_unix_time() : unixtime

  i2c.start()
  i2c.write($A4)
  i2c.write($1B)
  i2c.start()
  i2c.write($A5)
  i2c.rd_block(@unixtime, 4, i2c.NAK)
  i2c.stop()

CJMJ

Your generic_read method made me realize, when I started using your rd_block call I hadn't added the i2c.start() and i2c.write(slaveReadAddress) calls before it. Stupid mistake on my part. This damn hurricane has me distracted. Everything is working as expected now. Thanks for the help.

JonnyMac

Glad to help. I hope you and your family are safe from the storm.