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Topic: Two sainsmart relay board, Three ULN2803A and one Arduino Due (Read 273 times) previous topic - next topic

blackjack4

hi there, having:

Arduino Due (3.3V)
Three ULN2803A 8 I/O http://www.ti.com/lit/ds/symlink/uln2803a.pdf
Two https://www.sainsmart.com/products/16-channel-12v-relay-module

by plugging everything this way:

Digital Arduino outputs from 22 to 30 to I1-I2...I8 of the first ULN2803A
Digital Arduino outputs from 31 to 39 to I1-I2...I8 of the second ULN2803A
Digital Arduino outputs from 40 to 44 to I1-I2-I3-I4-I5 of the third ULN2803A

COMMONS
5V_1 of the first relay board to the COMMON pin of the first chip ULN2803A
5V_2 of the first relay board to the COMMON pin of the second chip ULN2803A
5V_1 of the second relay board to the COMMON pin of the third chip ULN2803A

GROUNDS
GND_1 of the first relay to the GND pin of the first chip ULN2803A
GND_2 of the first relay to the GND pin of the second chip ULN2803A
GND_1 of the second relay to the GND pin of the third chip ULN2803A
GND_2 of the second relay to the GND pin of the Arduino Due

OUTPUTS of RELAY BOARD
O1-O8 of the first chip plugged to R1-R8 inputs of the first relay board
O1-O8 of the second chip plugged to R9-R16 inputs of the first relay board
O1-O8 of the third chip  plugged to R1-R8 inputs of the second relay board

will any relay be HIGH if I will put HIGH on any digital arduino output? Am I doing everything right or my arduino will explode/burn/kill it self with fire?

because in a previous experiment an arduino has been seriously damaged with smoke using that scheme and I seriously don't know why! luckily it was an already broken one..the ATMEL chip blown up, but in theory there's no return from these ULN2803A chips
do you see any potential causes in my scheme?

Sorry if I am not posting a scheme, is my first setup so be patient please.

ard_newbie

I guess you would find relevant information in chapter 45 of Sam3X datasheet (Electrical charasteristics, from page 1378).

Maybe you sink too much current from the 22 PIOs. You have to be carefull with the max current you can sink from each PIO and from the total current the total PIO are actually using. Note that the maximum current you can draw from a DUE powered by a battery (9V) is 800 mA.


Since this is more an hardware issue, I guess you could have more answers in the General Electronics section of this forum if you asked the mod to move your thread.

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