Cytron Technical Forum

hi..

currently i'm doing a project which uses a wireless card.. that wireless card operates with 0V-2.7V for both Tx and Rx pin.. for communication testing purpose, i interface that card with with MAX232 circuit, which i connect Tx pin to T2in at MAX232 and Rx pin at R2out as in the attachment..

the problem is, by using serial comm monitor, i didn't manage to send and receive the data.. according to the manufacturer, the card has been tested and working well.. besides, i did test my MAX232 circuit and it works well.. any ideas?

az1 WROTE:hi..

currently i'm doing a project which uses a wireless card.. that wireless card operates with 0V-2.7V for both Tx and Rx pin.. for communication testing purpose, i interface that card with with MAX232 circuit, which i connect Tx pin to T2in at MAX232 and Rx pin at R2out as in the attachment..

the problem is, by using serial comm monitor, i didn't manage to send and receive the data.. according to the manufacturer, the card has been tested and working well.. besides, i did test my MAX232 circuit and it works well.. any ideas?

Of course. TX of the max232 should be connected to RX of the wireless card and vice versa.

ops.. my drawing supposed to be as attached.. my Tx is connected to R2out and Rx is connected to T2in..

back to the problem, as my wireless card operates with 0V-2.7V, is there any issues for MAX232?

thanks..

what is the wireless card ur are using? . are u sure the commands u sent to the wireless card is correct? are u sure that the wireless card can accept up to 3.3V?? u mentioned tat it operates up to 2.7V only? max232 can operate on 3.3V or 2.7V ??

im using Wavenis Wavecard.. attached, a screenshot for wavecard pin.. the card operates max 4.5V input supply..

az1 WROTE:im using Wavenis Wavecard.. attached, a screenshot for wavecard pin.. the card operates max 4.5V input supply..

The max232 requires 4.5V min to 5.5V max.

by using 3.3V, i have tested my MAX232 circuit by connecting directly pin T2out to pin R2in and i send "ABC" and the i manage to receive "ABC".. from this testing, i understand that my MAX232 circuit works well..

az1 WROTE:by using 3.3V, i have tested my MAX232 circuit by connecting directly pin T2out to pin R2in and i send "ABC" and the i manage to receive "ABC".. from this testing, i understand that my MAX232 circuit works well..

Did you try 2.7V voltage supply on the max232? Your tx and rx max is 2.7V.

yes.. i did try supply 2.7V to MAX232 and it's not working for MAX232 circuit either with or without (jump T2in with R2out) Wavecard.. besides, i understand that MAX232 operates with 3V min.

az1 WROTE:yes.. i did try supply 2.7V to MAX232 and it's not working for MAX232 circuit either with or without (jump T2in with R2out) Wavecard.. besides, i understand that MAX232 operates with 3V min.

Because max232 is not suppose to be use for 3.3v operation. Though, you can. Get MAX3223. Its a 3.3V device. It has something to do with the logic level. 2.7V in 3.3V TTL is consider high but, in 5V TTL its a different story. Do update us