I’ve been studying data sheets and have developed an opinion.
I don’t know if all of the following is true, so please correct as necessary.
We know that the old IF-E96E transmitter
in our application has been communicating with the old IF-D95T transmitters perfectly even under all driving conditions with the Tango for over 10 years. www.commutercars.com
We know that the IF-E96E cannot trigger a new IF-D95T, probably due to the addition of the lens to the design (circa 2014) further degrading dBm to the receiver.
We know that the IF-E96E required up to 30mA of power to operate and that the IF-E97 requires up to 40mA
Apparently we are not getting the required 1uW consistently to the IF-D95T receiver, which explains the uneven wave form, at 115,200 baud, instead of the 8.68uS square wave, we get 10-11us positive pulse width and a 6.36 to 7.36uS negative pulse width.
We know that both the IF-D96E and the IF-D97 suggest the use of an MC74ACT08 AND-gate to drive the transmitter which has a dynamic output current of 75mA.
Furthermore, the Avago SFH757, a competitive manufacturer’s data sheet recommends an SN75451BD IC PERIPHERAL DRIVER.
Apparently, according to the MC9S08DN60AMLF data sheet, page 113 below,
even with output set to “high drive strength” at 5V, it’s only capable o 10mA.
Doesn’t it look like we need to be sure that we’re supplying enough power to the IF-D95T to drive it properly, rather than directly from the DM9S08DN60AMLF processor, pin 11 in our case?
Is there any way to measure the uW output or mA input to a receiver to see how it compares with the data sheets and the maximum output from the processor?
Thanks in advance for clearing any misunderstanding that I have.