The DP most likely has one LED, while the segments have four.

The current limiting resistor has to be calculated for that.

Post a link to the display,

and post supply voltage and segment resistor values you're now using if you want help with that.

Leo..

Can't thank you enough for that, Leo.

Each segment resistor value = 220 ohm + original 15 ohm resistors from Sparkfun board.

Supply voltage to Sparkfun board = 12V (from VIN of UNO), so 12V to segment.

Only chain 2 pcs of 7-segment LED to UNO at this moment. The finish product will be 6 pcs.

Without 220 ohm resistors, DP segments are broken.

With 220 ohm resistors, no damage but after 2 hours of operation, the resistor of DP segment became very hot.

Here I attach the spec sheet of segment display.

Bronson